uva 10055,Hashmat the bravior

#include <stdio.h>
int main()
{
    unsigned long int a,b;

    while(scanf("%lu%lu", &a,&b)==2){
    if(a>b)
        printf("%lu\n",a-b);

    else
        printf("%lu\n",b-a);


    return 0;


}
}
//we can create an end of file by including the main code in a while/for loop.
//if end of file is not clear to u, u can ask question