#include <stdio.h>
#include <stdlib.h>


typedef struct NODE {
    int data;
    struct NODE* next;
}node;

node* top = NULL;
// Push Function
void push(int x)
{
    node *temp;
    temp = (node *) malloc(sizeof(node));
    temp -> data = x;
    temp -> next = top;
    top = temp;

}
// Pop function
int pop()
{
    node* temp;
    int num=0;
    temp = top;
    num = temp -> data;
    top = top -> next;
    free(temp);
    return num;
}

int Top()
{
    return top -> data;
}

void display(node *head)
{
    if(head == NULL) printf("NULL!n");
    else
    {
        printf("%dn", head -> data);
        display(head->next);
    }
}
int main() {
    int element,choice,val,tp;
    do
    {
    printf("---Stack Operations---n");
    printf("1.PUSHn");
    printf("2.POPn");
    printf("3.DISPLAYn");
    printf("4.Top elementn");
    printf("5.EXITn");
    printf("Enter an optionn");
    scanf("%d",&choice);

    switch(choice)
    {
        case 1:
        printf("Enter the element to pushn");
        scanf("%d",&val);
        push(val);
        break;

        case 2:
        element = pop();
        printf("Popped element is: %dn",element);
        break;

        case 3:
        display(top);
        break;

        case 4:
        tp = Top();
        printf("Top element is:%dn",tp);
        break;

        case 5:
        exit(0);
        default:
        printf("Enter a valid optionn");
        }
    }while(choice != 5);

}