What's wrong with my code for ceil A-B problem ?

Hi,
Here’s the code for Ceil A-B problem

#include<stdio.h>

int main()
{
unsigned long a=0;
unsigned long b=0;
scanf("%lu %lu", &a, &b);
printf("%lu\n", (a-b)^1);
return 0;
}

What’s wrong with this code ?
Please help me

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