byte rho(long x,int n){
  return (byte)(Long.numberOfLeadingZeros((x << (64 - n)) | (long)(1 << ((64 - n) - 1))) + 1);
}

byte rho ( long x , int n ) { return ( byte ) ( Long . numberOfLeadingZeros ( ( x << ( 64 - n ) ) | ( long ) ( 1 << ( ( 64 - n ) - 1 ) ) ) + 1 ) ; }
compute the number of leading 0s in the binary representation of ' x '
