diff --git a/2025.04.18/04Ex/solve.c b/2025.04.18/04Ex/solve.c
index 31ab1e3..48383d1 100644
--- a/2025.04.18/04Ex/solve.c
+++ b/2025.04.18/04Ex/solve.c
@@ -25,34 +25,23 @@ double t4_solve (
 			return DBL_MAX;
 		
 		Y[i+1] = (y_j - y_i) / (x_j - x_i);
-//		printf ("I = %d, f(x%d, ... , x%d) = %lf\n", i, i+1, i+2, Y[i+1]);
 
 		y_j = y_i;
 		x_j = x_i;
 	}
 
-//	for (int i = 1; i < n; ++i)
-//		printf ("f(x%d, x%d) = %lf\n", i-1, i, Y[i]);
-
 	for (int k = 1; k < n*2-1; ++k)
 	{
 		double f_j = D[n-1];
 
-//		printf ("------- K = %d -------\n", k);
-		
 		for (int l = n*2-2; l >= k; --l)
 		{
 			const int i = l >> 1;
 			double x_i, f_i, *f;
 			
-//			printf ("--- L = %d, I = %d ---\n", l , i); 
-
 			if (l & 1)
 			{
 				x_i = X[i-(k>>1)];
-//				printf ("f(x%d, ", i-(k>>1));
-//				for (int j = i-(k>>1)+1; j < i+(l&1); j++)
-//					printf ("x%d, ", j);
 
 				f_i = D[i];
 				f = Y + i + 1;
@@ -60,52 +49,29 @@ double t4_solve (
 			{
 				x_j = X[i];
 				x_i = X[i-(k>>1)-(k&1)];
-//				printf ("f(x%d, ", i-(k>>1)-(k&1));
-//				for (int j = i-(k>>1)-(k&1)+1; j < i+(l&1); j++)
-//					printf ("x%d, ", j);
+
 				f_i = Y[i];
 				f = D + i;
 			}
 
-//			printf ("x%d)\n", i+(l&1)); 
-
 			if (fabs(x_j - x_i) < DBL_EPSILON)
 				return DBL_MAX;
 			
 			*f = (f_j - f_i) / (x_j - x_i);
-//			printf ("f(x%d, x%d, ..., x%d) = %lf\n", i-k, i-k, i+1, Y[i+1]);
-//			printf ("f(x%d, ..., x%d, x%d) = %lf\n", i-k, i+1, i+1, D[i+1]);
-			
 			f_j = f_i;	
-			
-//			printf ("I = %d, f(x%d, ... , x%d) = %lf\n", i, i-k+1, i+2, Y[i+1]);
 		}
-
-//		printf("------- Y -------\n");
-//		for (int i = 0; i < n; ++i)
-//			printf("Y[%d] = %lf\n", i, Y[i]);
-
-//		printf("------- D -------\n");
-//		for (int i = 0; i < n; ++i)
-//			printf("D[%d] = %lf\n", i, D[i]);
 	}
 
 	start_value = 1;
 	value = 0;
 
-//	printf("------- Y -------\n");
-//	for (int i = 0; i < n; ++i)
-//		printf("Y[%d] = %lf\n", i, Y[i]);
-
-//	printf("------- D -------\n");
-//	for (int i = 0; i < n; ++i)
-//		printf("D[%d] = %lf\n", i, D[i]);
-
 	for (int i = 0; i < n; ++i)
 	{
 		const double diff = (x_0 - X[i]);
+
 		value += Y[i] * start_value;
 		start_value *= diff;
+
 		value += D[i] * start_value;
 		start_value *= diff;
 	}
diff --git a/2025.04.18/05Ex/Makefile b/2025.04.18/05Ex/Makefile
new file mode 100644
index 0000000..790c31a
--- /dev/null
+++ b/2025.04.18/05Ex/Makefile
@@ -0,0 +1,42 @@
+WFLAGS = -fstack-protector-all -W -Wall -Wextra -Wunused \
+-Wempty-body -Wlogical-op -Wold-style-declaration -Wmissing-parameter-type \
+-Wignored-qualifiers -Winit-self -Wshadow -Wtype-limits \
+-Wpointer-arith -Wformat-security -Wmissing-format-attribute -Wformat=1 \
+-Wdeclaration-after-statement -Wbad-function-cast -Wnested-externs \
+-Wmissing-prototypes -Wmissing-declarations -Wold-style-definition \
+-Wcast-align -Werror -pedantic -pedantic-errors -Wfloat-equal \
+-Wwrite-strings -Wno-long-long -std=gnu99 -Wstrict-prototypes \
+-Wmissing-field-initializers -Wpointer-sign
+
+CFLAGS = -std=gnu99 -mfpmath=sse -O3
+
+ifeq ($(OS),Windows_NT)
+	EXE = exe
+	CLEAN = del
+	LFLAGS = -lssp -lm
+else
+	EXE = out
+	CLEAN = rm -f
+	LFLAGS = -lm
+endif
+
+TARGET = a05.$(EXE)
+OBJ = main.o solve.o contin_func.o
+
+%.o: %.c
+	gcc $(CFLAGS) $(WFLAGS) -c $< -o $@
+
+$(TARGET): $(OBJ)
+	gcc $^ -o $@ $(LFLAGS)
+
+# Отладочная сборка (gdb)
+gdb: CFLAGS = -mfpmath=sse -std=gnu99 -g -O0
+gdb: clean $(TARGET)
+
+# Профилировочная сборка (gprof)
+prof: CFLAGS = -std=gnu99 -mfpmath=sse -pg -O3
+prof: LFLAGS = -lm -pg
+prof: clean $(TARGET)
+
+clean:
+	$(CLEAN) *.o *$(EXE)
diff --git a/2025.04.18/05Ex/contin_func.c b/2025.04.18/05Ex/contin_func.c
new file mode 100644
index 0000000..4267921
--- /dev/null
+++ b/2025.04.18/05Ex/contin_func.c
@@ -0,0 +1,38 @@
+#include "contin_func.h"
+
+#include <math.h>
+#include <float.h>
+
+double ssin (const double x, const double eps)
+{
+	double value = 0;
+	double el = x;
+	int i = 1;
+
+	while (fabs(el) - eps >= DBL_EPSILON)
+	{
+		value += el;
+
+		el *= -(x*x / (i*i + 3*i + 2));
+		i+=2;
+	}
+	
+	return value;
+}
+
+double scos (const double x, const double eps)
+{
+	double value = 0;
+	double el = 1;
+	int i = 0;
+
+	while (fabs(el) - eps >= DBL_EPSILON)
+	{
+		value += el;
+
+		el *= - (x*x / (i*i + 3*i + 2));
+		i+=2;
+	}
+	
+	return value;
+}
diff --git a/2025.04.18/05Ex/contin_func.h b/2025.04.18/05Ex/contin_func.h
new file mode 100644
index 0000000..404674a
--- /dev/null
+++ b/2025.04.18/05Ex/contin_func.h
@@ -0,0 +1,7 @@
+#ifndef CONTIN_FUNC_H
+#define CONTIN_FUNC_H
+
+double ssin (const double x, const double eps);
+double scos (const double x, const double eps);
+
+#endif
diff --git a/2025.04.18/05Ex/io_status.h b/2025.04.18/05Ex/io_status.h
new file mode 100644
index 0000000..4ab1d29
--- /dev/null
+++ b/2025.04.18/05Ex/io_status.h
@@ -0,0 +1,9 @@
+#ifndef IO_STATUS_H
+#define IO_STATUS_H
+
+#define ERR_MEM	"Error: Not enough memory!"
+#define ERR_OPEN "Error: Cannot open file"
+#define ERR_READ "Error: Cannot read file"
+#define ERR_FUNC "Error: Algorithm is not applicable!"
+
+#endif
diff --git a/2025.04.18/05Ex/main.c b/2025.04.18/05Ex/main.c
new file mode 100644
index 0000000..8edc338
--- /dev/null
+++ b/2025.04.18/05Ex/main.c
@@ -0,0 +1,34 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+#include <math.h>
+
+#include "io_status.h"
+#include "solve.h"
+
+/* ./a.out x eps */
+int main(int argc, char *argv[])
+{
+	double x, eps, t, r1 = 0, r2 = 0;
+	int task = 5;
+
+	if (
+			!((argc == 3) && 
+			sscanf(argv[1], "%lf", &x) == 1 &&
+			((sscanf(argv[2], "%lf", &eps) == 1) && eps > 0))
+	) {
+		fprintf(stderr, "Usage: %s x eps\n", argv[0]);
+		return 1;
+	}
+
+	t = clock();
+	r1 = fsin(x, eps);
+	t = (clock() - t) / CLOCKS_PER_SEC;
+
+	r2 = fabs(r1 - sin(x));
+
+	printf("%s : Task = %d Result = %e Residual = %e Elapsed = %.2f\n", argv[0], task, r1, r2, t);
+
+	return 0;
+}
+
diff --git a/2025.04.18/05Ex/solve.c b/2025.04.18/05Ex/solve.c
new file mode 100644
index 0000000..de8b757
--- /dev/null
+++ b/2025.04.18/05Ex/solve.c
@@ -0,0 +1,49 @@
+#include "solve.h"
+#include "contin_func.h"
+
+#include <stdlib.h>
+#include <math.h>
+#include <float.h>
+
+double fsin (double x, const double eps)
+{
+	double answer;
+	short flag = 1;
+
+	if (-x > DBL_EPSILON)
+	{
+		x = -x;
+		flag = -1;
+	}
+	
+	if (x - M_PI*2 >= DBL_EPSILON)
+		x = fmod(x, M_PI*2);
+
+	if (x - M_PI >= DBL_EPSILON)
+	{
+		x -= M_PI;
+		flag *= -1;
+	}
+
+	if (x - M_PI_2 >= DBL_EPSILON)
+	{
+		x -= M_PI_2;
+		flag *= 2;
+	}
+
+	if (abs(flag) == 2)
+	{
+		double cosinus, sinus;
+		x /= 2;
+
+		cosinus = scos(x, eps);
+		sinus = ssin(x, eps);
+
+		answer = ((flag > 0) - (flag < 0)) * (cosinus * cosinus - sinus * sinus);
+	} else
+		answer = flag * ssin(x, eps);
+
+	return answer;
+}
+
+
diff --git a/2025.04.18/05Ex/solve.h b/2025.04.18/05Ex/solve.h
new file mode 100644
index 0000000..af4ece9
--- /dev/null
+++ b/2025.04.18/05Ex/solve.h
@@ -0,0 +1,6 @@
+#ifndef SOLVE_H
+#define SOLVE_H
+
+double fsin (double x, const double eps);
+
+#endif
diff --git a/2025.04.18/dist/Krivoruchenko_SK/Makefile b/2025.04.18/dist/Krivoruchenko_SK/Makefile
new file mode 100644
index 0000000..cbfc3d3
--- /dev/null
+++ b/2025.04.18/dist/Krivoruchenko_SK/Makefile
@@ -0,0 +1,15 @@
+FLAGS = -fstack-protector-all -W -Wall -Wextra -Wunused -Wcast-align -Werror -pedantic -pedantic-errors -Wfloat-equal -Wpointer-arith -Wformat-security -Wmissing-format-attribute -Wformat=1 -Wwrite-strings -Wcast-align -Wno-long-long -std=gnu99 -Wstrict-prototypes -Wmissing-prototypes -Wmissing-declarations -Wold-style-definition -Wdeclaration-after-statement -Wbad-function-cast -Wnested-externs -O3
+
+%.out: %.o solve.o array_io.o contin_func.o
+	 gcc $(FLAGS) $^ -o $@ -lm
+%.o: %.c
+	 gcc -c $(FLAGS) $<
+
+all: a01.out a02.out a03.out a04.out a05.out
+
+solve.o: solve.c solve.h
+array_io.o: array_io.c array_io.h
+contin_func.o: contin_func.c contin_func.h
+
+clean:
+	 rm -f *.o *.out
diff --git a/2025.04.18/dist/Krivoruchenko_SK/a01.c b/2025.04.18/dist/Krivoruchenko_SK/a01.c
new file mode 100644
index 0000000..84c3501
--- /dev/null
+++ b/2025.04.18/dist/Krivoruchenko_SK/a01.c
@@ -0,0 +1,85 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+#include <float.h>
+#include <math.h>
+
+#include "array_io.h"
+#include "io_status.h"
+#include "solve.h"
+
+/* ./a.out x_0 n filename */
+int main(int argc, char *argv[])
+{
+	double x_0, t, r = 0, *X = 0, *Y = 0;
+	int n, task = 1;
+	char *name = 0;
+	io_status ret;
+
+	if (
+			!((argc == 4) && 
+			sscanf(argv[1], "%lf", &x_0) == 1 &&
+			((sscanf(argv[2], "%d", &n) == 1) && n > 0) &&
+			((name = argv[3]) && name))
+	) {
+		fprintf(stderr, "Usage: %s x_0 n filename\n", argv[0]);
+		return 1;
+	}
+
+	X = (double *)malloc(n * sizeof(double));
+	if (!X)
+	{
+		fprintf(stderr, "%s\n", ERR_MEM);
+		return 2;
+	}
+	
+	Y = (double *)malloc(n * sizeof(double));
+	if (!Y)
+	{
+		free(X);
+		fprintf(stderr, "%s\n", ERR_MEM);
+		return 2;
+	}
+
+	ret = read_values(X, Y, n, name);
+	do {
+		switch (ret)
+		{
+			case SUCCESS:
+				continue;
+			case ERROR_OPEN:	
+				fprintf(stderr, "%s '%s'!\n", ERR_OPEN, name);
+				break;
+			case ERROR_READ:
+				fprintf(stderr, "%s '%s'!\n", ERR_READ, name);
+				break;
+		}
+
+		free(X);
+		free(Y);
+
+		return 3; 
+	} while (0);
+
+	t = clock();
+	r = t1_solve(x_0, n, X, Y);
+	t = (clock() - t) / CLOCKS_PER_SEC;
+	
+	if (fabs(r - DBL_MAX) < DBL_EPSILON)
+	{
+		fprintf(stderr, "%s\n", ERR_FUNC);
+
+		free(X);
+		free(Y);
+
+		return 4;
+	}
+
+	printf("%s : Task = %d Result = %e Elapsed = %.2f\n", argv[0], task, r, t);
+
+	free(X);
+	free(Y);
+
+	return 0;
+}
+
diff --git a/2025.04.18/dist/Krivoruchenko_SK/a02.c b/2025.04.18/dist/Krivoruchenko_SK/a02.c
new file mode 100644
index 0000000..19baa42
--- /dev/null
+++ b/2025.04.18/dist/Krivoruchenko_SK/a02.c
@@ -0,0 +1,85 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+#include <float.h>
+#include <math.h>
+
+#include "array_io.h"
+#include "io_status.h"
+#include "solve.h"
+
+/* ./a.out x_0 n filename */
+int main(int argc, char *argv[])
+{
+	double x_0, t, r = 0, *X = 0, *Y = 0;
+	int n, task = 2;
+	char *name = 0;
+	io_status ret;
+
+	if (
+			!((argc == 4) && 
+			sscanf(argv[1], "%lf", &x_0) == 1 &&
+			((sscanf(argv[2], "%d", &n) == 1) && n > 0) &&
+			((name = argv[3]) && name))
+	) {
+		fprintf(stderr, "Usage: %s x_0 n filename\n", argv[0]);
+		return 1;
+	}
+
+	X = (double *)malloc(n * sizeof(double));
+	if (!X)
+	{
+		fprintf(stderr, "%s\n", ERR_MEM);
+		return 2;
+	}
+	
+	Y = (double *)malloc(n * sizeof(double));
+	if (!Y)
+	{
+		free(X);
+		fprintf(stderr, "%s\n", ERR_MEM);
+		return 2;
+	}
+
+	ret = read_values(X, Y, n, name);
+	do {
+		switch (ret)
+		{
+			case SUCCESS:
+				continue;
+			case ERROR_OPEN:	
+				fprintf(stderr, "%s '%s'!\n", ERR_OPEN, name);
+				break;
+			case ERROR_READ:
+				fprintf(stderr, "%s '%s'!\n", ERR_READ, name);
+				break;
+		}
+
+		free(X);
+		free(Y);
+
+		return 3; 
+	} while (0);
+
+	t = clock();
+	r = t2_solve(x_0, n, X, Y);
+	t = (clock() - t) / CLOCKS_PER_SEC;
+	
+	if (fabs(r - DBL_MAX) < DBL_EPSILON)
+	{
+		fprintf(stderr, "%s\n", ERR_FUNC);
+
+		free(X);
+		free(Y);
+
+		return 4;
+	}
+
+	printf("%s : Task = %d Result = %e Elapsed = %.2f\n", argv[0], task, r, t);
+
+	free(X);
+	free(Y);
+
+	return 0;
+}
+
diff --git a/2025.04.18/dist/Krivoruchenko_SK/a03.c b/2025.04.18/dist/Krivoruchenko_SK/a03.c
new file mode 100644
index 0000000..3c86193
--- /dev/null
+++ b/2025.04.18/dist/Krivoruchenko_SK/a03.c
@@ -0,0 +1,85 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+#include <float.h>
+#include <math.h>
+
+#include "array_io.h"
+#include "io_status.h"
+#include "solve.h"
+
+/* ./a.out x_0 n filename */
+int main(int argc, char *argv[])
+{
+	double x_0, t, r = 0, *X = 0, *Y = 0;
+	int n, task = 3;
+	char *name = 0;
+	io_status ret;
+
+	if (
+			!((argc == 4) && 
+			sscanf(argv[1], "%lf", &x_0) == 1 &&
+			((sscanf(argv[2], "%d", &n) == 1) && n > 0) &&
+			((name = argv[3]) && name))
+	) {
+		fprintf(stderr, "Usage: %s x_0 n filename\n", argv[0]);
+		return 1;
+	}
+
+	X = (double *)malloc(n * sizeof(double));
+	if (!X)
+	{
+		fprintf(stderr, "%s\n", ERR_MEM);
+		return 2;
+	}
+	
+	Y = (double *)malloc(n * sizeof(double));
+	if (!Y)
+	{
+		free(X);
+		fprintf(stderr, "%s\n", ERR_MEM);
+		return 2;
+	}
+
+	ret = read_values(X, Y, n, name);
+	do {
+		switch (ret)
+		{
+			case SUCCESS:
+				continue;
+			case ERROR_OPEN:	
+				fprintf(stderr, "%s '%s'!\n", ERR_OPEN, name);
+				break;
+			case ERROR_READ:
+				fprintf(stderr, "%s '%s'!\n", ERR_READ, name);
+				break;
+		}
+
+		free(X);
+		free(Y);
+
+		return 3; 
+	} while (0);
+
+	t = clock();
+	r = t3_solve(x_0, n, X, Y);
+	t = (clock() - t) / CLOCKS_PER_SEC;
+
+	if (fabs(r - DBL_MAX) < DBL_EPSILON)
+	{
+		fprintf(stderr, "%s\n", ERR_FUNC);
+
+		free(X);
+		free(Y);
+
+		return 4;
+	}
+		
+	printf("%s : Task = %d Result = %e Elapsed = %.2f\n", argv[0], task, r, t);
+
+	free(X);
+	free(Y);
+
+	return 0;
+}
+
diff --git a/2025.04.18/dist/Krivoruchenko_SK/a04.c b/2025.04.18/dist/Krivoruchenko_SK/a04.c
new file mode 100644
index 0000000..d9c323b
--- /dev/null
+++ b/2025.04.18/dist/Krivoruchenko_SK/a04.c
@@ -0,0 +1,97 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+#include <float.h>
+#include <math.h>
+
+#include "array_io.h"
+#include "io_status.h"
+#include "solve.h"
+
+/* ./a.out x_0 n filename */
+int main(int argc, char *argv[])
+{
+	double x_0, t, r = 0, *X = 0, *Y = 0, *D = 0;
+	int n, task = 4;
+	char *name = 0;
+	io_status ret;
+
+	if (
+			!((argc == 4) && 
+			sscanf(argv[1], "%lf", &x_0) == 1 &&
+			((sscanf(argv[2], "%d", &n) == 1) && n > 0) &&
+			((name = argv[3]) && name))
+	) {
+		fprintf(stderr, "Usage: %s x_0 n filename\n", argv[0]);
+		return 1;
+	}
+
+	X = (double *)malloc(n * sizeof(double));
+	if (!X)
+	{
+		fprintf(stderr, "%s\n", ERR_MEM);
+		return 2;
+	}
+	
+	Y = (double *)malloc(n * sizeof(double));
+	if (!Y)
+	{
+		free(X);
+		fprintf(stderr, "%s\n", ERR_MEM);
+		return 2;
+	}
+
+	D = (double *)malloc(n * sizeof(double));
+	if (!D)
+	{
+		free(X);
+		free(Y);
+		fprintf(stderr, "%s\n", ERR_MEM);
+		return 2;
+	}
+
+	ret = read_values_and_derivatives(X, Y, D, n, name);
+	do {
+		switch (ret)
+		{
+			case SUCCESS:
+				continue;
+			case ERROR_OPEN:	
+				fprintf(stderr, "%s '%s'!\n", ERR_OPEN, name);
+				break;
+			case ERROR_READ:
+				fprintf(stderr, "%s '%s'!\n", ERR_READ, name);
+				break;
+		}
+
+		free(X);
+		free(Y);
+		free(D);
+
+		return 3; 
+	} while (0);
+
+	t = clock();
+	r = t4_solve(x_0, n, X, Y, D);
+	t = (clock() - t) / CLOCKS_PER_SEC;
+
+	if (fabs(r - DBL_MAX) < DBL_EPSILON)
+	{
+		fprintf(stderr, "%s\n", ERR_FUNC);
+
+		free(X);
+		free(Y);
+		free(D);
+
+		return 4;
+	}
+		
+	printf("%s : Task = %d Result = %e Elapsed = %.2f\n", argv[0], task, r, t);
+
+	free(X);
+	free(Y);
+	free(D);
+
+	return 0;
+}
+
diff --git a/2025.04.18/dist/Krivoruchenko_SK/a05.c b/2025.04.18/dist/Krivoruchenko_SK/a05.c
new file mode 100644
index 0000000..8edc338
--- /dev/null
+++ b/2025.04.18/dist/Krivoruchenko_SK/a05.c
@@ -0,0 +1,34 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+#include <math.h>
+
+#include "io_status.h"
+#include "solve.h"
+
+/* ./a.out x eps */
+int main(int argc, char *argv[])
+{
+	double x, eps, t, r1 = 0, r2 = 0;
+	int task = 5;
+
+	if (
+			!((argc == 3) && 
+			sscanf(argv[1], "%lf", &x) == 1 &&
+			((sscanf(argv[2], "%lf", &eps) == 1) && eps > 0))
+	) {
+		fprintf(stderr, "Usage: %s x eps\n", argv[0]);
+		return 1;
+	}
+
+	t = clock();
+	r1 = fsin(x, eps);
+	t = (clock() - t) / CLOCKS_PER_SEC;
+
+	r2 = fabs(r1 - sin(x));
+
+	printf("%s : Task = %d Result = %e Residual = %e Elapsed = %.2f\n", argv[0], task, r1, r2, t);
+
+	return 0;
+}
+
diff --git a/2025.04.18/dist/Krivoruchenko_SK/array_io.c b/2025.04.18/dist/Krivoruchenko_SK/array_io.c
new file mode 100644
index 0000000..109cfe0
--- /dev/null
+++ b/2025.04.18/dist/Krivoruchenko_SK/array_io.c
@@ -0,0 +1,59 @@
+#include <stdio.h>
+#include <string.h>
+#include "array_io.h"
+
+io_status read_values (double * restrict X, double * restrict Y, const int n, const char * restrict name)
+{
+	FILE *fp;
+	if (!(fp = fopen(name, "r"))) 
+		return ERROR_OPEN;
+
+	for (int i = 0; i < n; ++i)
+		if (fscanf(fp, "%lf\t%lf", X + i, Y + i) != 2)
+		{ fclose(fp); return ERROR_READ; }
+
+	fclose(fp);
+	return SUCCESS;
+}
+
+io_status read_values_and_derivatives (
+		double * restrict X, 
+		double * restrict Y, 
+		double * restrict D, 
+		const int n, 
+		const char * restrict name
+		)
+{
+	FILE *fp;
+	if (!(fp = fopen(name, "r"))) 
+		return ERROR_OPEN;
+
+	for (int i = 0; i < n; ++i)
+		if (fscanf(fp, "%lf\t%lf\t%lf", X + i, Y + i, D + i) != 3)
+		{ fclose(fp); return ERROR_READ; }
+
+	fclose(fp);
+	return SUCCESS;
+}
+
+void print_values (const double * restrict X, const double * restrict Y, const int n, const int p)
+{
+	int np = (n > p ? p : n);
+
+	for (int i = 0; i < np; i++)
+		printf("f(%lf) = %lf\n", X[i], Y[i]);
+}
+
+void print_values_and_derivatives (
+		const double * restrict X, 
+		const double * restrict Y, 
+		const double * restrict D, 
+		const int n, const int p
+		) 
+{
+	int np = (n > p ? p : n);
+
+	for (int i = 0; i < np; i++)
+		printf("f(%lf) = %lf, f`(%lf) = %lf\n", X[i], Y[i], X[i], D[i]);
+}
+
diff --git a/2025.04.18/dist/Krivoruchenko_SK/array_io.h b/2025.04.18/dist/Krivoruchenko_SK/array_io.h
new file mode 100644
index 0000000..cabb8d8
--- /dev/null
+++ b/2025.04.18/dist/Krivoruchenko_SK/array_io.h
@@ -0,0 +1,22 @@
+#ifndef ARRAY_IO_H
+#define ARRAY_IO_H
+
+#include "io_status.h"
+
+io_status read_values (double * restrict X, double * restrict Y, const int n, const char * restrict name);
+void print_values (const double * restrict X, const double * restrict Y, const int n, const int p);
+io_status read_values_and_derivatives (
+		double * restrict X, 
+		double * restrict Y, 
+		double * restrict D, 
+		const int n, 
+		const char * restrict name
+		);
+void print_values_and_derivatives (
+		const double * restrict X, 
+		const double * restrict Y, 
+		const double * restrict D, 
+		const int n, const int p
+		);
+
+#endif
diff --git a/2025.04.18/dist/Krivoruchenko_SK/contin_func.c b/2025.04.18/dist/Krivoruchenko_SK/contin_func.c
new file mode 100644
index 0000000..4267921
--- /dev/null
+++ b/2025.04.18/dist/Krivoruchenko_SK/contin_func.c
@@ -0,0 +1,38 @@
+#include "contin_func.h"
+
+#include <math.h>
+#include <float.h>
+
+double ssin (const double x, const double eps)
+{
+	double value = 0;
+	double el = x;
+	int i = 1;
+
+	while (fabs(el) - eps >= DBL_EPSILON)
+	{
+		value += el;
+
+		el *= -(x*x / (i*i + 3*i + 2));
+		i+=2;
+	}
+	
+	return value;
+}
+
+double scos (const double x, const double eps)
+{
+	double value = 0;
+	double el = 1;
+	int i = 0;
+
+	while (fabs(el) - eps >= DBL_EPSILON)
+	{
+		value += el;
+
+		el *= - (x*x / (i*i + 3*i + 2));
+		i+=2;
+	}
+	
+	return value;
+}
diff --git a/2025.04.18/dist/Krivoruchenko_SK/contin_func.h b/2025.04.18/dist/Krivoruchenko_SK/contin_func.h
new file mode 100644
index 0000000..404674a
--- /dev/null
+++ b/2025.04.18/dist/Krivoruchenko_SK/contin_func.h
@@ -0,0 +1,7 @@
+#ifndef CONTIN_FUNC_H
+#define CONTIN_FUNC_H
+
+double ssin (const double x, const double eps);
+double scos (const double x, const double eps);
+
+#endif
diff --git a/2025.04.18/dist/Krivoruchenko_SK/io_status.h b/2025.04.18/dist/Krivoruchenko_SK/io_status.h
new file mode 100644
index 0000000..8867bee
--- /dev/null
+++ b/2025.04.18/dist/Krivoruchenko_SK/io_status.h
@@ -0,0 +1,16 @@
+#ifndef IO_STATUS_H
+#define IO_STATUS_H
+
+#define ERR_MEM	"Error: Not enough memory!"
+#define ERR_OPEN "Error: Cannot open file"
+#define ERR_READ "Error: Cannot read file"
+#define ERR_FUNC "Error: Algorithm is not applicable!"
+
+typedef enum _io_status
+{
+	SUCCESS,
+	ERROR_OPEN,
+	ERROR_READ
+} io_status;
+
+#endif
diff --git a/2025.04.18/dist/Krivoruchenko_SK/solve.c b/2025.04.18/dist/Krivoruchenko_SK/solve.c
new file mode 100644
index 0000000..dc0422a
--- /dev/null
+++ b/2025.04.18/dist/Krivoruchenko_SK/solve.c
@@ -0,0 +1,224 @@
+#include "solve.h"
+#include "contin_func.h"
+
+#include <stdlib.h>
+#include <float.h>
+#include <math.h>
+
+// the Lagrange interpolation polynomial
+double t1_solve (const double x_0, const int n, const double * restrict X, const double * restrict Y)
+{
+	double value = 0;
+
+	for (int i = 0; i < n; ++i)
+	{
+		double x_i = X[i];
+		double y_i = Y[i];
+		
+		double numerator = y_i;
+		double denominator = 1;
+
+		if (fabs(x_0 - x_i) < DBL_EPSILON)
+			return y_i;
+
+		for (int j = 0; j < i; ++j)
+		{
+			double x_j = X[j];
+			numerator *= (x_0 - x_j);
+			denominator *= (x_i - x_j);
+		}
+
+		for (int j = i+1; j < n; ++j)
+		{
+			double x_j = X[j];
+			numerator *= (x_0 - x_j);
+			denominator *= (x_i - x_j);
+		}
+
+		if (fabs(denominator) < DBL_EPSILON)
+			return DBL_MAX;
+		
+		value += numerator / denominator;
+	}
+
+	return value;
+}
+
+// the Newton interpolation polynomial
+double t2_solve (const double x_0, const int n, const double * restrict X, double * restrict Y)
+{
+	double value, start_value;
+
+	for (int k = 0; k < n-1; ++k)
+	{
+		double last_x; 
+		double last_y = Y[n-1];
+		
+		for (int i = n-2; i >= k; --i)
+		{
+			const double x_i = X[i-k];
+			const double y_i = Y[i];
+			last_x = X[i+1];
+			
+			if (fabs(last_x - x_i) < DBL_EPSILON)
+				return DBL_MAX;
+			
+			Y[i+1] = (last_y - y_i) / (last_x - x_i);
+
+			last_y = y_i;
+		}
+	}
+
+	start_value = 1;
+	value = 0;
+
+	for (int i = 0; i < n; ++i)
+	{
+		value += Y[i] * start_value;
+		start_value *= (x_0 - X[i]);
+	}
+
+	return value;
+}
+
+// Interpolation polynomial according to Aitken's scheme
+double t3_solve (const double x_0, const int n, const double * restrict X, double * restrict Y)
+{
+	for (int k = 0; k < n-1; ++k)
+	{
+		double x_j; 
+		double y_j = Y[n-1];
+		
+		for (int i = n-2; i >= k; --i)
+		{
+			const double x_i = X[i-k];
+			const double y_i = Y[i];
+			x_j = X[i+1];
+			
+			if (fabs(x_j - x_i) < DBL_EPSILON)
+				return DBL_MAX;
+			
+			Y[i+1] = ((x_0-x_i) * y_j - (x_0-x_j) * y_i) / (x_j - x_i);
+
+			y_j = y_i;
+		}
+	}
+
+	return Y[n-1];
+}
+
+// Newton's interpolation polynomial with derivative
+double t4_solve (
+		const double x_0, const int n, 
+		const double * restrict X, 
+		double * restrict Y,
+		double * restrict D
+		)
+{
+	double value, start_value;
+	double x_j = X[n-1];
+	double y_j = Y[n-1];
+
+	for (int i = n-2; i >= 0; --i)
+	{
+		const double x_i = X[i];
+		const double y_i = Y[i];
+		
+		if (fabs(x_j - x_i) < DBL_EPSILON)
+			return DBL_MAX;
+		
+		Y[i+1] = (y_j - y_i) / (x_j - x_i);
+
+		y_j = y_i;
+		x_j = x_i;
+	}
+
+	for (int k = 1; k < n*2-1; ++k)
+	{
+		double f_j = D[n-1];
+
+		for (int l = n*2-2; l >= k; --l)
+		{
+			const int i = l >> 1;
+			double x_i, f_i, *f;
+			
+			if (l & 1)
+			{
+				x_i = X[i-(k>>1)];
+
+				f_i = D[i];
+				f = Y + i + 1;
+			} else 
+			{
+				x_j = X[i];
+				x_i = X[i-(k>>1)-(k&1)];
+
+				f_i = Y[i];
+				f = D + i;
+			}
+
+			if (fabs(x_j - x_i) < DBL_EPSILON)
+				return DBL_MAX;
+			
+			*f = (f_j - f_i) / (x_j - x_i);
+			f_j = f_i;	
+		}
+	}
+
+	start_value = 1;
+	value = 0;
+
+	for (int i = 0; i < n; ++i)
+	{
+		const double diff = (x_0 - X[i]);
+
+		value += Y[i] * start_value;
+		start_value *= diff;
+
+		value += D[i] * start_value;
+		start_value *= diff;
+	}
+
+	return value;
+}
+
+double fsin (double x, const double eps)
+{
+	double answer;
+	short flag = 1;
+
+	if (-x > DBL_EPSILON)
+	{
+		x = -x;
+		flag = -1;
+	}
+	
+	if (x - M_PI*2 >= DBL_EPSILON)
+		x = fmod(x, M_PI*2);
+
+	if (x - M_PI >= DBL_EPSILON)
+	{
+		x -= M_PI;
+		flag *= -1;
+	}
+
+	if (x - M_PI_2 >= DBL_EPSILON)
+	{
+		x -= M_PI_2;
+		flag *= 2;
+	}
+
+	if (abs(flag) == 2)
+	{
+		double cosinus, sinus;
+		x /= 2;
+
+		cosinus = scos(x, eps);
+		sinus = ssin(x, eps);
+
+		answer = ((flag > 0) - (flag < 0)) * (cosinus * cosinus - sinus * sinus);
+	} else
+		answer = flag * ssin(x, eps);
+
+	return answer;
+}
diff --git a/2025.04.18/dist/Krivoruchenko_SK/solve.h b/2025.04.18/dist/Krivoruchenko_SK/solve.h
new file mode 100644
index 0000000..f81212d
--- /dev/null
+++ b/2025.04.18/dist/Krivoruchenko_SK/solve.h
@@ -0,0 +1,15 @@
+#ifndef SOLVE_H
+#define SOLVE_H
+
+double t1_solve (const double x_0, const int n, const double * restrict X, const double * restrict Y);
+double t2_solve (const double x_0, const int n, const double * restrict X, double * restrict Y);
+double t3_solve (const double x_0, const int n, const double * restrict X, double * restrict Y);
+double t4_solve (
+		const double x_0, const int n, 
+		const double * restrict X, 
+		double * restrict Y,
+		double * restrict D
+		);
+double fsin (double x, const double eps);
+
+#endif