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

int main(int argc, char **argv)
{
  int N = 0;

  if(argc > 1)
    {
      N = atoi(argv[1]);
    }
  else
    {
      printf("Please specify a number to factor...\n");
      exit(1);
    }

  if(N <= 0)
    {
      printf("'%s' doesn't appear to be a number greater than zero...\n",argv[1]);
      exit(1);
    }

  int base,x,xsqr;
  int y,ysqr;

  base = sqrt(N);

  // check for square root
  if(base * base == N)
    {
      printf("Factorization: %d = %d * %d\n",N,base,base);
      exit(0);
    }

  int count = 0;
  for(x = base+1; (float)x * (float)x < (float)MAXINT && (count < (2 * N)); x++)
    {
      xsqr = x * x;
      ysqr = xsqr - N;

      y = (int)sqrt((double)ysqr);

      if(y * y == ysqr)
	{
	  // both x+y and x-y should be a factor of N
	  int factor1, factor2;

	  // check x+y
	  factor1 = x+y;
	  if((factor1 != N) && (factor1 != 1) && (N % factor1 == 0))
	    {
	      factor2 = N / factor1;
	      printf("Factorization: %d = %d * %d\n",N,factor1,factor2);
	      exit(0);
	    }
	}
      count++;
    }
  printf("No non-trivial factorization found for %d\n",N);

}