#include <stdio.h>
#include <stdlib.h>
 
#define MAX 5  // Maximum size of stack
 
int stack[MAX];
int top = -1;
 
// Function to push an element into the stack
void push(int value) {
    if (top == MAX - 1) {
        printf("\nStack Overflow! Cannot push %d\n", value);
    } else {
        top++;
        stack[top] = value;
        printf("\n%d pushed to stack.\n", value);
    }
}
 
// Function to pop an element from the stack
void pop() {
    if (top == -1) {
        printf("\nStack Underflow! No elements to pop.\n");
    } else {
        printf("\n%d popped from stack.\n", stack[top]);
        top--;
    }
}
 
// Function to display stack elements
void display() {
    if (top == -1) {
        printf("\nStack is empty.\n");
    } else {
        printf("\nStack elements are:\n");
        for (int i = top; i >= 0; i--) {
            printf("%d\n", stack[i]);
        }
    }
}
 
// Function to view the top element
void peek() {
    if (top == -1) {
        printf("\nStack is empty.\n");
    } else {
        printf("\nTop element is: %d\n", stack[top]);
    }
}
 
// Main function (menu-driven)
int main() {
    int choice, value;
 
    printf("=== STACK IMPLEMENTATION USING ARRAY ===\n");
 
    while (1) {
        printf("\nMenu:\n");
        printf("1. Push\n");
        printf("2. Pop\n");
        printf("3. Peek\n");
        printf("4. Display\n");
        printf("5. Exit\n");
        printf("Enter your choice: ");
        scanf("%d", &choice);
 
        switch (choice) {
            case 1:
                printf("Enter value to push: ");
                scanf("%d", &value);
                push(value);
                break;
            case 2:
                pop();
                break;
            case 3:
                peek();
                break;
            case 4:
                display();
                break;
            case 5:
                printf("\nExiting program.\n");
                exit(0);
            default:
                printf("\nInvalid choice! Try again.\n");
        }
    }
 
    return 0;
}