Stack using C Language

This is a very simple stack progam using C language

#include <stdio.h>
#include<stdlib.h>
#define MAX 9
int stack[10];
int top=-1;
void push(int item)
{
 if(top==MAX)
 {
  printf("\nOver Flow.....");
  return;
 }
 else
 {
  top=top+1;
  stack[top]=item;
 }
}
int pop()
{
 int a;
 if(top==-1)
 {
  printf("\nUnder flow......");
  return -1;
 }
 else
 {
  a=stack[top];
  top=top-1;
  return a;
 }
}
void display()
{
 int i;
 for(i=0;i<=top;i++)
 {
  printf("\nPosition: %d\tVaue: %d",i,stack[i]);
 }
}
void main()
{
 int c,item;
 while(1)
 {
  printf("\n1.Push\n2.Pop\n3.Display\n4.Exit");
  printf("\nEnter your choice: ");
  scanf("%d",&c);
  switch(c)
  {
   case 1:
    printf("Enter item to insert: ");
    scanf("%d",&item);
    push(item);
    break;
   case 2:
    item=pop();
    if(item!=-1)
     printf("\n%d is deleted",item);
    break;
   case 3:
    display();
    break;
   case 4:
    exit(0);
   default:
    printf("\nWrong choice");
  }
 }
}

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