PALIN: running in my pc but not here.

Here is the code:

#include<stdio.h>
#include<string.h>
short ispalindrome(unsigned long);

int main()
{
unsigned int t;

scanf("%u",&t);
while(t--)
{   unsigned long input;
    scanf("%lu",&input);
    while(input<1000000&&input>=11)
    {
        if(ispalindrome(++input))
        {
            printf("%lu\n",input);
            break;
        }
    }
    if(input<11) printf("11\n");
}
return 0;
}
short ispalindrome(unsigned long y)
{
char buff[7];
unsigned int i,j;
sprintf(buff,"%u\0",y);
j=strlen(buff);
for(i=0;i<=j/2-1;i++)
{
  if(buff[i]!=buff[j-1-i])
  {
  return 0;
  }
 }
 return 1;
 }

This program running in my pc correctly. Here it’s saying wrong answer. Pls help me what’s wrong with my program ?

The value of k is not less than 1000000, it is a 1000000 digit long number. (say 1 followed by 1000000 zeroes). Take input in a string and use appropriate algorithm.

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