#include<math.h>
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<time.h>
#include<png.h>

typedef int _;
typedef double f;

png_image i;
png_bytep m[2];
_ C,H,A,R,L,O,t,T,E;
f b[17][17][2], d, x, y;

_ c(_ u, char *v)
{
   return printf(u ? u - 1 ? "Error writing %s\n"
                           : "Error reading %s\n"
                   : "%s <input.png> <output1.png> <output2.png>\n",
                 v);
}

f r()
{
   return (f)rand() / RAND_MAX - 0.5;
}

f q(f U, f V, f u, f v)
{
   return U * u + V * v;
}

f p(f u, f v, f w)
{
   return w < 0
      ? u
      : w > 1 ? v
              : (v - u) * (w * (w * 6 - 15) + 10) * w * w * w + u;
}

_ main(_ a, char **z)
{
   if( a - 4 )
      return c(0, *z);

   i.version = PNG_IMAGE_VERSION;
   if( png_image_begin_read_from_file(&i, z[1]) )
   {
      i.format = PNG_FORMAT_RGBA;
      L = i.width;
      R = i.height;
      for(H = 0; H < 2;)
         m[H++] = (png_bytep)malloc(C = L * R * 4);
      A = *m && m[1] &&
          png_image_finish_read(&i, NULL, *m, 0, NULL);
   }
   if( !A )
      return c(1, z[1]);

   memcpy(m[1], *m, C);
   srand(time(NULL));

   for(A = 0; A < 17; A++)
      for(H = 0; H < 17; b[A][H++][1] = y / d)
      {
         for(x = y = 0; (d = hypot(x, y)) < 1e-6; y = r())
            x = r();
         b[A][H][0] = x / d;
      }
   d = (f)(L > R ? L : R) / 16;

   for(A = C = 0; A < R; A++)
      for(O = floor(y = A / d), H = 0; H < L; H++, C += 4)
      {
         t = floor(x = H / d);
         T = t + 1;
         E = O + 1;

         memset(
            m
            [
               (sizeof('c') > 1
                 ? 0.25
                 : p(p(q(b[O][t][0],
                         b[O][t][1],
                         t - x,
                         O - y),
                       q(b[O][T][0],
                         b[O][T][1],
                         T - x,
                         O - y),
                       x - t),
                     p(q(b[E][t][0],
                         b[E][t][1],
                         t - x,
                         E - y),
                       q(b[E][T][0],
                         b[E][T][1],
                         T - x,
                         E - y),
                       x - t),
                     y - O)) > r()
            ] + C,
            0,
            4);
      }

   for(H = 0; H < 2; H++)
      if( !png_image_write_to_file(&i, z[2 + H], 0, m[H], 0, NULL) )
         return c(2, z[2 + H]);
   return 0;
}