STACKofIntegers

#include <stdio.h>
#include <stdlib.h>
#define MAX 5
int STACK[MAX],top=-1;
int isEmpty()
{
  if(top==-1)
    return 1;
  else
    return 0;
}
int isFull()
{
  if(top==MAX-1)
    return 1;
  else
    return 0;
}
int PUSH(int elem)
{
  if(isFull())
  {
    printf("\nStack Overflow. Please remove an element before adding a new one");
    return -1;
  }
  else
    return STACK[++top]=elem;
}
int POP()
{
  if(isEmpty())
  {
    printf("\nStack Underflow. Please insert an element before removing");
    return -1;
  }
  else
    return STACK[top--];
}
void status()
{
  if(isEmpty())
  {
    printf("\nStack Underflow");
    return;
  }
  else
  {
    if(isFull())
      printf("\nStack Overflow");
    printf("\nThe elements of the STACK are: ");
    for(int i=0;i<=top;i++)
      printf("%d ",STACK[i]);
  }
}
void palindrome()
{
  int num;
  printf("\nEnter the number to be checked: ");
  scanf("%d",&num);
  int backupNum=num;
  while(!isEmpty())
    POP();
  while(!isFull() && num>0)
  {
    STACK[++top]=num%10;
    num/=10;
  }
  if(isFull() && num>0 )
  {
    printf("\nStack Overflow");
    return;
  }
  num=backupNum;
  while(num>0)
  {
    if(num%10!=POP())
    {
      printf("\nThe entered number is not a palindrome");
      return;
    }
    num/=10;
  }
  printf("\nThe entered number is a palindrome");
}
void exitProgram()
{
  printf("\nThank you for using the program");
  exit(0);
}
int main()
{
  int choice;
  while(1)
  {
    printf("\n\n1)\tPush an Element on to Stack\n2)\tPop an Element from Stack\n3)\tCheck for Palindrome\n4)\tDisplay the Status of STACK\n5)\tExit\n>|");
    scanf("%d",&choice);
    switch (choice)
    {
      case 1:
      {
        int elem;
        printf("\nEnter the element to be pushed in to the STACK: ");
        scanf("%d",&elem);
        if(PUSH(elem)!=-1)
          printf("\n%d was added to the stack",elem);
      }
      break;
      case 2:
      {
        int result=POP();
        if(result!=-1)
          printf("\n%d was removed from the stack",result);
      }
      break;
      case 3:
        palindrome();
      break;
      case 4:
        status();
      break;
      case 5:
        exitProgram();
      break;
      default:
        printf("\nIncorrect choice. Please retry\n");
    }
  }
}