/*program to output maximal palindrom of a number
 *uses a recursive dunction "reverse" 
 *
 * Author:rahule@cse.iitk.ac.in
 */

#include<stdio.h>
int reverse(int);
main()
{
  int n,pal,t,p;
  printf("\nEnter the number :");
  scanf("%d",&n);
  
  while(n)	//run this loop till n becomes 0 or till a maximal palindrom is found
  {
    if(n==reverse(n))	//if n = reverse(n),then n is the maximal palindrom..so break
      break;
    t=n;p=1;
    //follwing code strikes off first and last digit of the number
    while(t)	//calulates p such that p is 1 followed by x zeros,where x is the number of digits in 'n'
    {
      p=p*10;
      t=t/10;
    }
    p=p/10;		//strikes out last 0 in p
    n=n%p;		//strikes out first digit in n
    n=n/10;		//strikes out last digit in n
  }
  printf("\nthe maximal palindrom :%d",n);
}


int reverse(int n)
//function to reverse n
{
  int p=1,t,d,temp;
  if(n/10==0)		//if n has only one digit,return that
    return(n);
  else
  {
    p=1;
    t=n;
    while(t)
    {
      p=p*10;
      t=t/10;
    }
    p=p/10;		
    d=n/p;	//takes the first digit of n in d	
    
    return(reverse(n%p)*10+d);	//reverses therest of the digits and appends d to it
  }
}