diff --git a/src/23oct25/main.c b/src/23oct25/main.c
new file mode 100644
index 0000000..f228fd9
--- /dev/null
+++ b/src/23oct25/main.c
@@ -0,0 +1,47 @@
+#include <stdio.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include "../stack/stack.h"
+
+bool isBalanced(const char* str) {
+    struct Stack* stack = new();
+    bool balanced = true;
+
+    for (int i = 0; str[i] != '\0'; i++) {
+        char ch = str[i];
+        if (ch == '(' || ch == '[' || ch == '{') {
+            stack = push(stack, ch);
+        } else if (ch == ')' || ch == ']' || ch == '}') {
+            if (stack == NULL) {
+                balanced = false;
+                break;
+            }
+
+            int top;
+            stack = pop(stack, &top);
+
+            if ((ch == ')' && top != '(') || (ch == ']' && top != '[') || (ch == '}' && top != '{')) {
+                balanced = false;
+                break;
+            }
+        }
+    }
+    
+    if (stack != NULL) {
+        balanced = false;
+        delete(stack);
+    }
+    
+    return balanced;
+}
+
+int main(void) {
+    const char* tests[] = {"()", "[]", "{}", "({})", "({)}", "((()))", "([{}])", "}{", "(", ")", ""};
+    int numTests = sizeof(tests) / sizeof(tests[0]);
+
+    for (int i = 0; i < numTests; i++) {
+        printf("String: \"%s\" is %s\n", tests[i], isBalanced(tests[i]) ? "сбалансирована" : "не сбалансирована");
+    }
+
+    return 0;
+}
diff --git a/src/stack/stack.c b/src/stack/stack.c
new file mode 100644
index 0000000..e2e6315
--- /dev/null
+++ b/src/stack/stack.c
@@ -0,0 +1,53 @@
+#include <stdlib.h>
+#include "stack.h"
+
+struct Stack {
+    int value;
+    struct Stack* next;
+};
+
+struct Stack* push(struct Stack* stack, int value)
+{
+    struct Stack* newStack = malloc(sizeof(struct Stack));
+
+    if (!newStack)
+        return NULL;
+
+    newStack->value = value;
+    newStack->next = stack;
+    return newStack;
+}
+
+struct Stack* pop(struct Stack* stack, int* value) 
+{
+    if (stack == NULL)
+        return NULL;
+
+    struct Stack* temp = stack->next;
+    *value = stack->value;
+    free(stack);
+    return temp;
+}
+
+int peek(struct Stack* stack) 
+{
+    if (stack == NULL)
+        return -1;
+
+    return stack->value;
+}
+
+struct Stack* new(void) 
+{
+    return NULL;
+}
+
+void delete(struct Stack* stack) 
+{
+    while (stack != NULL) {
+        struct Stack* temp = stack;
+        stack = stack->next;
+        free(temp);
+    }
+}
+
diff --git a/src/stack/stack.h b/src/stack/stack.h
new file mode 100644
index 0000000..babbcde
--- /dev/null
+++ b/src/stack/stack.h
@@ -0,0 +1,18 @@
+#pragma once 
+
+struct Stack;
+
+// Создает новый стек с NULL
+struct Stack* new(void);
+
+// Кладет элемент на стек и возвращает измененный стек
+struct Stack* push(struct Stack* stack, int value);
+
+// Берет элемент со стек, возвращает измененный стек, сохраняет удаленное значение в аргумент value
+struct Stack* pop(struct Stack* stack, int* value);
+
+// Возвращает верхний элемент стека
+int peek(struct Stack* stack);
+
+// Удаляет весь стек
+void delete(struct Stack* stack);
\ No newline at end of file