#include<stdio.h>
#include<stdlib.h>
void push(int s[],int item);
int pop(int s[]);
void display();
# define stacksize 4
int s[stacksize];
int top=-1;
int main()
{
    int ch,item;
    while(1)
    {
        printf("\n");
        scanf("%d",&ch);
        switch(ch)
        {
            case 1 : scanf("%d",&item);
                     push(s,item);break;
            case 2 : pop(s);break;
            case 3 : display();break;
            case 4 : if(top==-1)
                      {
                         printf("Empty stack- No peek\n");
                      }
                      else
                      {
                          printf("The top most element in stack is :%d\n",s[top]);
                      };break;
            case 5 : exit(0);
            default : printf("Invalid Choice");
            //exit(0);
        }
    }
    return 0;
}
void push(int s[],int item)
{
    if(top==stacksize-1)
    {
        printf("Stack Overflow-Cannot Push\n");
        return;
    }
    top = top+1;
    s[top]=item;
}
int pop(int s[])
{
    if(top==-1)
    {
        printf("Stack Underflow-Cannot Pop\n");
        return 0;
    }
    printf("The popped element  is :%d\n",s[top--]);
}
void display()
{
    if(top==-1)
    {
        printf("Stack is Empty-No elements to Display\n");
        return;
    }
    for(int i=top;i>=0;i--)
    {
        printf("%d\n",s[i]);
    }
}