#include <stdio.h>
#include <math.h>

unsigned long fsqrt(unsigned long n)
{
  return (unsigned long)sqrt(n);
}

unsigned long isqrt(unsigned long n)
{
  unsigned int a;
  for (a = 0;
       n >= (2 * a) + 1;
       n -= (2 * a++) + 1);
  return a;
}

int main(void)
{
  unsigned long i = 0;
  while (i++ < 0xffffff) {
    if (fsqrt(i) != isqrt(i)) {
      printf("fsqrt(%lu)=%lu isqrt(%lu)=%lu\n",
        i, fsqrt(i), i, isqrt(i));
    }
  }
  printf("done.\n");
  return 0;
}