pe66

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

int main()
{
  int d, x, y, sx, sy, fx, fy, max = 0;

  for (d=100; d<=1000; d++)
  {
    if (sqrtf(d) == (int)sqrtf(d)) continue;

    for (x=1, sx=1;; x++)
    {
      sx = x*x;

      for (y=1, sy=1; sx > d*sy+1; y++)
      {
        sy = y*y;
        if (sx - d*sy == 1) break;
      }

      if (sx - d*sy == 1)
      {
        fx = x, fy = y;
        if (fx > max) max = fx;
        printf("%d^2 - %d*%d^2 = 1\n",fx,d,fy);
        break;
      }
    }
  }

  printf("max=%d\n",max);
}