BEGIN  { 
    printf ("P3\n256 256\n255\n");
    for (i = 0; i < 256; i++ )
      { for (j = 0; j < 256; j++ )
          printf ( "%3d %3d %3d\n", 255*rand() , 255*rand() , 255*rand());
        printf("\n");
      }
  }