function bc(n) {
  n = ((n >> 1) & 0x55555555 ) + (n & 0x55555555);
  n = ((n >> 4) & 0xC30C30C3) +
      ((n  >> 2) & 0xC30C30C3) + (n & 0xC30C30C3);
  n = ((n >> 6) & 0x3F03F03F) + (n & 0x3F03F03F);
  n = ((n >> 12) & 0xFF000FFF) + (n & 0xFF000FFF);
  return n = ((n >> 24) & 0x00FFFFF) + (n & 0x00FFFFF);
}