diff --git a/2025.05.23/dist/Kochubei_DS/a01.c b/2025.05.23/dist/Kochubei_DS/a01.c
index cd7e041..4159fe2 100644
--- a/2025.05.23/dist/Kochubei_DS/a01.c
+++ b/2025.05.23/dist/Kochubei_DS/a01.c
@@ -26,19 +26,16 @@ int main(int argc, char** argv)
     if (status==-1)
     {
         printf("Cannot open file\n");
-        delete_node(N);
         return -1;
     }
     else if (status==-2)
     {
         printf("Cannot read file\n");
-        delete_node(N);
         return -2;
     }
     else if (status==3)
     {
         printf("Cannot allocate memory\n");
-        delete_node(N);
         return -2;
     }
     print_node(p, N);
diff --git a/2025.05.23/dist/Kochubei_DS/a02.c b/2025.05.23/dist/Kochubei_DS/a02.c
index 2bf9f1b..3ce2441 100644
--- a/2025.05.23/dist/Kochubei_DS/a02.c
+++ b/2025.05.23/dist/Kochubei_DS/a02.c
@@ -26,19 +26,16 @@ int main(int argc, char** argv)
     if (status==-1)
     {
         printf("Cannot open file\n");
-        delete_node(N);
         return -1;
     }
     else if (status==-2)
     {
         printf("Cannot read file\n");
-        delete_node(N);
         return -2;
     }
     else if (status==3)
     {
         printf("Cannot allocate memory\n");
-        delete_node(N);
         return -2;
     }
     print_node(p, N);
diff --git a/2025.05.23/dist/Kochubei_DS/a03.c b/2025.05.23/dist/Kochubei_DS/a03.c
index 18f017f..fd160fe 100644
--- a/2025.05.23/dist/Kochubei_DS/a03.c
+++ b/2025.05.23/dist/Kochubei_DS/a03.c
@@ -26,19 +26,16 @@ int main(int argc, char** argv)
     if (status==-1)
     {
         printf("Cannot open file\n");
-        delete_node(N);
         return -1;
     }
     else if (status==-2)
     {
         printf("Cannot read file\n");
-        delete_node(N);
         return -2;
     }
     else if (status==3)
     {
         printf("Cannot allocate memory\n");
-        delete_node(N);
         return -2;
     }
     print_node(p, N);
diff --git a/2025.05.23/dist/Kochubei_DS/a04.c b/2025.05.23/dist/Kochubei_DS/a04.c
index c74fcaa..e3e0649 100644
--- a/2025.05.23/dist/Kochubei_DS/a04.c
+++ b/2025.05.23/dist/Kochubei_DS/a04.c
@@ -26,19 +26,16 @@ int main(int argc, char** argv)
     if (status==-1)
     {
         printf("Cannot open file\n");
-        delete_node(N);
         return -1;
     }
     else if (status==-2)
     {
         printf("Cannot read file\n");
-        delete_node(N);
         return -2;
     }
     else if (status==3)
     {
         printf("Cannot allocate memory\n");
-        delete_node(N);
         return -2;
     }
     print_node(p, N);
diff --git a/2025.05.23/dist/Kochubei_DS/a05.c b/2025.05.23/dist/Kochubei_DS/a05.c
index adacb25..9cb942b 100644
--- a/2025.05.23/dist/Kochubei_DS/a05.c
+++ b/2025.05.23/dist/Kochubei_DS/a05.c
@@ -26,19 +26,16 @@ int main(int argc, char** argv)
     if (status==-1)
     {
         printf("Cannot open file\n");
-        delete_node(N);
         return -1;
     }
     else if (status==-2)
     {
         printf("Cannot read file\n");
-        delete_node(N);
         return -2;
     }
     else if (status==3)
     {
         printf("Cannot allocate memory\n");
-        delete_node(N);
         return -2;
     }
     print_node(p, N);
diff --git a/2025.05.23/dist/Kochubei_DS/a06.c b/2025.05.23/dist/Kochubei_DS/a06.c
index 1512eb8..7e4c702 100644
--- a/2025.05.23/dist/Kochubei_DS/a06.c
+++ b/2025.05.23/dist/Kochubei_DS/a06.c
@@ -26,19 +26,16 @@ int main(int argc, char** argv)
     if (status==-1)
     {
         printf("Cannot open file\n");
-        delete_node(N);
         return -1;
     }
     else if (status==-2)
     {
         printf("Cannot read file\n");
-        delete_node(N);
         return -2;
     }
     else if (status==3)
     {
         printf("Cannot allocate memory\n");
-        delete_node(N);
         return -2;
     }
     print_node(p, N);
diff --git a/2025.05.23/dist/Kochubei_DS/a07.c b/2025.05.23/dist/Kochubei_DS/a07.c
index 1f8928f..75ab68b 100644
--- a/2025.05.23/dist/Kochubei_DS/a07.c
+++ b/2025.05.23/dist/Kochubei_DS/a07.c
@@ -26,19 +26,16 @@ int main(int argc, char** argv)
     if (status==-1)
     {
         printf("Cannot open file\n");
-        delete_node(N);
         return -1;
     }
     else if (status==-2)
     {
         printf("Cannot read file\n");
-        delete_node(N);
         return -2;
     }
     else if (status==3)
     {
         printf("Cannot allocate memory\n");
-        delete_node(N);
         return -2;
     }
     print_node(p, N);
diff --git a/2025.05.23/dist/Kochubei_DS/a08.c b/2025.05.23/dist/Kochubei_DS/a08.c
index bada0a2..c853c3c 100644
--- a/2025.05.23/dist/Kochubei_DS/a08.c
+++ b/2025.05.23/dist/Kochubei_DS/a08.c
@@ -26,19 +26,16 @@ int main(int argc, char** argv)
     if (status==-1)
     {
         printf("Cannot open file\n");
-        delete_node(N);
         return -1;
     }
     else if (status==-2)
     {
         printf("Cannot read file\n");
-        delete_node(N);
         return -2;
     }
     else if (status==3)
     {
         printf("Cannot allocate memory\n");
-        delete_node(N);
         return -2;
     }
     print_node(p, N);
diff --git a/2025.05.23/dist/Kochubei_DS/a09.c b/2025.05.23/dist/Kochubei_DS/a09.c
index 1fe6672..64fb189 100644
--- a/2025.05.23/dist/Kochubei_DS/a09.c
+++ b/2025.05.23/dist/Kochubei_DS/a09.c
@@ -26,19 +26,16 @@ int main(int argc, char** argv)
     if (status==-1)
     {
         printf("Cannot open file\n");
-        delete_node(N);
         return -1;
     }
     else if (status==-2)
     {
         printf("Cannot read file\n");
-        delete_node(N);
         return -2;
     }
     else if (status==3)
     {
         printf("Cannot allocate memory\n");
-        delete_node(N);
         return -2;
     }
     print_node(p, N);
diff --git a/2025.05.23/dist/Kochubei_DS/a10.c b/2025.05.23/dist/Kochubei_DS/a10.c
index d6aa531..2e6ec5c 100644
--- a/2025.05.23/dist/Kochubei_DS/a10.c
+++ b/2025.05.23/dist/Kochubei_DS/a10.c
@@ -26,19 +26,16 @@ int main(int argc, char** argv)
     if (status==-1)
     {
         printf("Cannot open file\n");
-        delete_node(N);
         return -1;
     }
     else if (status==-2)
     {
         printf("Cannot read file\n");
-        delete_node(N);
         return -2;
     }
     else if (status==3)
     {
         printf("Cannot allocate memory\n");
-        delete_node(N);
         return -2;
     }
     print_node(p, N);
diff --git a/2025.05.23/dist/Kochubei_DS/add.c b/2025.05.23/dist/Kochubei_DS/add.c
index 7094a28..cd83038 100644
--- a/2025.05.23/dist/Kochubei_DS/add.c
+++ b/2025.05.23/dist/Kochubei_DS/add.c
@@ -157,11 +157,11 @@ void delete_node(node* head)
     while(1)
     {
         node* pointer;
+            if (head==0) break;
         free(head->string);
         pointer=head;
         head=head->next;
         free(pointer);
-        if (head==0) break;
     }
 }
 
diff --git a/2025.05.23/dist/Kochubei_DS/inputs/empty.txt b/2025.05.23/dist/Kochubei_DS/inputs/empty.txt
new file mode 100644
index 0000000..e69de29
diff --git a/2025.05.23/dist/Kochubei_DS/inputs/one.txt b/2025.05.23/dist/Kochubei_DS/inputs/one.txt
new file mode 100755
index 0000000..3c858ac
--- /dev/null
+++ b/2025.05.23/dist/Kochubei_DS/inputs/one.txt
@@ -0,0 +1 @@
+hello 109
\ No newline at end of file
diff --git a/2025.05.23/dist/Kochubei_DS/inputs/test.txt b/2025.05.23/dist/Kochubei_DS/inputs/test.txt
new file mode 100755
index 0000000..7455be8
--- /dev/null
+++ b/2025.05.23/dist/Kochubei_DS/inputs/test.txt
@@ -0,0 +1,19 @@
+a
+b
+a
+b
+a
+b
+b
+b
+b
+b
+a
+b
+c
+d
+e
+e
+e
+f
+f
\ No newline at end of file
diff --git a/2025.05.23/dist/Kochubei_DS/inputs/two.txt b/2025.05.23/dist/Kochubei_DS/inputs/two.txt
new file mode 100755
index 0000000..98d42a4
--- /dev/null
+++ b/2025.05.23/dist/Kochubei_DS/inputs/two.txt
@@ -0,0 +1,2 @@
+
+second line
\ No newline at end of file
diff --git a/2025.05.23/dist/Kochubei_DS/solve.c b/2025.05.23/dist/Kochubei_DS/solve.c
index a03fee1..22f19ef 100644
--- a/2025.05.23/dist/Kochubei_DS/solve.c
+++ b/2025.05.23/dist/Kochubei_DS/solve.c
@@ -332,6 +332,215 @@ node* solve8(node* head)
 
 }
 
+
+
+node* solve9(node* head)
+{
+    node* tmp1;
+    node* tmp2;
+    node* tmp3;
+    int was_thrown=0;
+    int last_eq=0;
+    tmp1=head;
+    if (head->next==0)
+    {
+        return head;
+    }
+    if (head->next->next==0)
+    {
+        return head;
+    }
+    tmp1=head;
+    tmp2=head->next;
+    tmp3=head->next->next;
+    while(tmp3->next!=0)
+    {
+        if (was_thrown==0)
+        {
+            if (strcmp(tmp1->string, tmp2->string)<=0 && strcmp(tmp2->string, tmp3->string)>=0)
+            {
+                if (strcmp(tmp2->string, tmp3->string)==0)
+                {
+                    last_eq=1;
+                }
+                else
+                {
+                    last_eq=0;
+                }
+                free(tmp2->string);
+                tmp2->string=0;
+                was_thrown=1;
+            }
+            else
+            {
+                was_thrown=0;
+            }
+        }
+        else
+        {
+            if (last_eq==1 && strcmp(tmp2->string, tmp3->string)>=0)
+            {
+                if (strcmp(tmp2->string, tmp3->string)==0)
+                {
+                    last_eq=1;
+                }
+                else
+                {
+                    last_eq=0;
+                }
+                free(tmp2->string);
+                tmp2->string=0;
+                was_thrown=1;
+            }
+            else
+            {
+                was_thrown=0;
+            }
+        }
+        tmp1=tmp2;
+        tmp2=tmp3;
+        tmp3=tmp3->next;
+    }
+    tmp1=head;
+    tmp2=head->next;
+    tmp3=head->next->next;
+    while(1)
+    {
+        if (tmp2->string==0)
+        {
+            free(tmp2);
+            tmp1->next=tmp3;
+            if (tmp3->next==0)
+            {
+                break;
+            }
+            tmp2=tmp3;
+            tmp3=tmp3->next;
+        }
+        else
+        {
+            if (tmp3->next==0)
+            {
+                break;
+            }
+            tmp1=tmp2;
+            tmp2=tmp3;
+            tmp3=tmp3->next;
+        }
+    }
+    return head;
+}
+
+
+
+
+node* solve10(node* head)
+{
+    node* tmp1;
+    node* tmp2;
+    node* tmp3;
+    int last=0;
+    if (head->next==0)
+    {
+        return head;
+    }
+    tmp1=head;
+    tmp2=head->next;
+    while(1)
+    {
+        if (strcmp(tmp1->string, tmp2->string)>=0)
+        {
+            free(tmp1->string);
+            tmp1->string=0;
+            last=1;
+        }
+        else
+        {
+            if (last==1)
+            {
+                free(tmp1->string);
+                tmp1->string=0;
+                last=0;
+            }
+        }
+        if (tmp2->next==0)
+        {
+            break;
+        }
+        tmp1=tmp2;
+        tmp2=tmp2->next;
+    }
+
+    if (last==1)
+    {
+        free(tmp2->string);
+        tmp2->string=0;
+    }
+    tmp1=head;
+    tmp2=head->next;
+    if (head->next->next==0)
+    {
+        if (tmp1->string==0)
+        {
+            free(tmp1);
+            free(tmp2);
+            return 0;
+        }
+        else
+        {
+            return head;
+        }
+    }
+    tmp3=head->next->next;
+    while(1)
+    {
+        if (tmp2->string==0)
+        {
+            free(tmp2);
+            tmp1->next=tmp3;
+            if (tmp3->next==0)
+            {
+                if (tmp3->string==0)
+                {
+                    tmp1->next=0;
+                    free(tmp3);
+                }
+                break;
+            }
+            tmp2=tmp3;
+            tmp3=tmp3->next;
+        }
+        else
+        {
+            if (tmp3->next==0)
+            {
+                if (tmp3->string==0)
+                {
+                    tmp2->next=0;
+                    free(tmp3);
+                }
+                break;
+            }
+            tmp1=tmp2;
+            tmp2=tmp3;
+            tmp3=tmp3->next;
+        }
+    }
+    if (head->string==0)
+    {
+        node* ret=head->next;
+        free(head);
+        return ret;
+    }
+    return head;
+}
+
+
+
+
+
+
+/*/
 node* solve9(node* head)
 {
     char s[1]={'\0'};
@@ -423,7 +632,6 @@ node* solve9(node* head)
     return head;
 }
 
-
 node* solve10(node* head)
 {
 
@@ -499,7 +707,7 @@ node* solve10(node* head)
 
 
 
-/*/
+
 node* solve10(node* head)
 {
     int flag=0;
@@ -540,7 +748,7 @@ node* solve10(node* head)
                 copy_node(ptr2, &tmp2);
                 copy_node(ptr3, &tmp3);
                 flag=0;
-                
+
                 ptr1->next=ptr3;
                 free(ptr2->string);
                 free(ptr2);
@@ -584,7 +792,7 @@ node* solve10(node* head)
             printf("DELETED 1\n");
             print_node(100, base.next);
         }
-        
+
         else
         {
             if (flag==1)
@@ -601,7 +809,7 @@ node* solve10(node* head)
                 copy_node(ptr2, &tmp2);
                 copy_node(ptr3, &tmp3);
                 flag=0;
-                
+
                 ptr1->next=ptr3;
                 free(ptr2->string);
                 free(ptr2);
@@ -629,7 +837,7 @@ node* solve10(node* head)
             }
 
         }
-        
+
     }
     return base.next;
 }