diff --git a/5.Stack-and-Quene/Stack/stack.c b/5.Stack-and-Quene/Stack/stack.c
new file mode 100644
index 0000000..f23663f
--- /dev/null
+++ b/5.Stack-and-Quene/Stack/stack.c
@@ -0,0 +1,74 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include "stack.h"
+
+
+OBJ* stack_new(void)
+{
+    return NULL;
+}
+
+OBJ* stack_push(OBJ* top, char data)
+{
+    OBJ* ptr = malloc(sizeof(OBJ));
+    ptr->data = data;
+    ptr->next = top;
+
+    return ptr;
+}
+
+// Взять элемент со стека
+OBJ* stack_pop(OBJ* top)
+{
+    if(top == NULL)
+    {
+        printf("Стек пуст\n");
+        return top;
+    }
+
+    OBJ* ptr_next = top->next;
+    free(top);
+
+    return ptr_next;
+}
+
+OBJ* stack_delete(OBJ* top)
+{
+    OBJ* current = top;
+    while (current != NULL)
+    {
+        OBJ* temp = current;
+        current = current->next;
+        free(temp);
+    }
+    
+    return 0;
+}
+
+// Функция для просмотра элемента сверху
+char stack_peek(const OBJ* top)
+{
+    if(top == NULL)
+    {
+        printf("Стек пуст\n");
+        return -1;
+    }
+
+    return top->data;
+}
+
+void show(const OBJ* top)
+{
+    const OBJ* current = top;
+    if(top == NULL)
+    {
+        printf("Стек пуст\n");
+        return;
+    }
+
+    while(current != NULL)
+    {
+        printf("%d\n", current->data);
+        current = current->next;
+    }
+}
diff --git a/5.Stack-and-Quene/Stack/stack.h b/5.Stack-and-Quene/Stack/stack.h
new file mode 100644
index 0000000..83434cc
--- /dev/null
+++ b/5.Stack-and-Quene/Stack/stack.h
@@ -0,0 +1,28 @@
+#ifndef STACK_H
+#define STACK_H
+
+typedef struct tag_obj
+{
+    char data;
+    struct tag_obj* next;
+} OBJ;
+
+// Создание нового стека
+OBJ* stack_new(void);
+
+// Добавление элемента на стек
+OBJ* stack_push(OBJ* top, char data);
+
+// Удаление верхнего элемента
+OBJ* stack_pop(OBJ* top);
+
+// Удаление стека
+OBJ* stack_delete(OBJ* top);
+
+// Просмотр верхнего элемента
+char stack_peek(const OBJ* top);
+
+// Вывод содержимого
+void stack_show(OBJ* top);
+
+#endif
\ No newline at end of file
diff --git a/5.Stack-and-Quene/Task_2/Sorting-yard.c b/5.Stack-and-Quene/Task_2/Sorting-yard.c
new file mode 100644
index 0000000..a027cee
--- /dev/null
+++ b/5.Stack-and-Quene/Task_2/Sorting-yard.c
@@ -0,0 +1,118 @@
+#include <stdio.h>
+#include <string.h>
+#include <ctype.h>
+#include "../Stack/stack.h"
+
+
+int precedence(char op) 
+{
+    switch(op) 
+    {
+        case '+':
+        case '-':
+            return 1;
+
+        case '*':
+        case '/':
+            return 2;
+
+        default:
+            return 0;
+    }
+}
+
+int is_operator(char c)
+{
+    return c == '+' || c == '-' || c == '*' || c == '/';
+}
+
+char* infix_to_postfix(const char* infix)
+{
+    static char output[1000];
+    output[0] = '\0';
+
+    OBJ* stack = stack_new();
+    int output_index = 0;
+
+    for (int i = 0; infix[i] != '\0'; i++) 
+    {
+        char token = infix[i];
+        
+        if (isspace(token)) 
+        {
+            continue;
+        }
+        
+        if (isdigit(token)) 
+        {
+            while (isdigit(infix[i])) 
+            {
+                output[output_index++] = infix[i++];
+            }
+            
+            output[output_index++] = ' ';
+            i--;
+        }
+
+        else if (token == '(') 
+        {
+            stack = stack_push(stack, token);
+        }
+
+        else if (token == ')') 
+        {
+            while (stack != NULL && stack_peek(stack) != '(')
+            {
+                output[output_index++] = stack_peek(stack);
+                output[output_index++] = ' ';
+                stack = stack_pop(stack);
+            }
+
+            if (stack != NULL && stack_peek(stack) == '(')
+            {
+                stack = stack_pop(stack);
+            }
+        }
+
+        else if (is_operator(token)) 
+        {
+            while (stack != NULL && stack_peek(stack) != '(' && 
+                   precedence(stack_peek(stack)) >= precedence(token)) 
+            {
+                output[output_index++] = stack_peek(stack);
+                output[output_index++] = ' ';
+                stack = stack_pop(stack);
+            }
+
+            stack = stack_push(stack, token);
+        }
+    }
+
+    while (stack != NULL) 
+    {
+        output[output_index++] = stack_peek(stack);
+        output[output_index++] = ' ';
+        stack = stack_pop(stack);
+    }
+
+    if (output_index > 0 && output[output_index-1] == ' ') 
+    {
+        output_index--;
+    }
+    
+    output[output_index] = '\0';
+    stack_delete(stack);
+    return output;
+}
+
+int main() {
+    char infix[1000];
+    
+    printf("Введите инфиксное выражение: ");
+    scanf("%999[^\n]", infix);
+    
+    char* postfix = infix_to_postfix(infix);
+    printf("Постфиксная запись: %s\n", postfix);
+    
+    return 0;
+}
\ No newline at end of file
diff --git a/Stack/stack.c b/Stack/stack.c
new file mode 100644
index 0000000..51cb4a7
--- /dev/null
+++ b/Stack/stack.c
@@ -0,0 +1,80 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include "stack.h"
+
+
+typedef struct tag_obj
+{
+    int data;
+    struct tag_obj* next;
+} OBJ;
+
+OBJ* stack_new(void)
+{
+    return NULL;
+}
+
+OBJ* stack_push(OBJ* top, int data)
+{
+    OBJ* ptr = malloc(sizeof(OBJ));
+    ptr->data = data;
+    ptr->next = top;
+
+    return ptr;
+}
+
+// Взять элемент со стека
+OBJ* stack_pop(OBJ* top)
+{
+    if(top == NULL)
+    {
+        printf("Стек пуст\n");
+        return top;
+    }
+
+    OBJ* ptr_next = top->next;
+    free(top);
+
+    return ptr_next;
+}
+
+OBJ* stack_delete(OBJ* top)
+{
+    OBJ* current = top;
+    while (current != NULL)
+    {
+        OBJ* temp = current;
+        current = current->next;
+        free(temp);
+    }
+    
+    return 0;
+}
+
+// Функция для просмотра элемента сверху
+int stack_peek(const OBJ* top)
+{
+    if(top == NULL)
+    {
+        printf("Стек пуст\n");
+        return -1;
+    }
+
+    return top->data;
+}
+
+void show(const OBJ* top)
+{
+    const OBJ* current = top;
+    if(top == NULL)
+    {
+        printf("Стек пуст\n");
+        return;
+    }
+
+    while(current != NULL)
+    {
+        printf("%d\n", current->data);
+        current = current->next;
+    }
+}
diff --git a/Stack/stack.h b/Stack/stack.h
new file mode 100644
index 0000000..ee80b5f
--- /dev/null
+++ b/Stack/stack.h
@@ -0,0 +1,28 @@
+#ifdef STACK_H
+#define STACK_H
+
+typedef struct tag_obj
+{
+    int data;
+    struct tag_obj* next;
+} OBJ;
+
+// Создание нового стека
+OBJ* stack_new(void);
+
+// Добавление элемента на стек
+OBJ* stack_push(OBJ* top, int data);
+
+// Удаление верхнего элемента
+OBJ* stack_pop(OBJ* top);
+
+// Удаление стека
+OBJ* stack_delete(OBJ* top);
+
+// Просмотр верхнего элемента
+int stack_peek(OBJ* top);
+
+// Вывод содержимого
+void stack_show(OBJ* top);
+
+#endif
\ No newline at end of file