#! perl -slw
use strict;
use Inline C => << '__C__', NAME => "_627288"; # => CLEAN_AFTER_BUILD => 0;
#include <stdio.h>

int fc( double x, double y, int d ) {
    double bsize = pow( 4, ( d-1 ) );

    if( x == y )
        return d;
    else if( (int)( x / 4 ) == (int)( y / 4 ) )
        return d-1;
    else if( (int)( x / bsize ) == (int)( y / bsize ) )
        return 1 + fc( fmod( x, bsize ), fmod( y, bsize ), d-1 );
    else
        return     fc( fmod( x, bsize ), fmod( y, bsize ), d-1 );
}

__C__

sub f{
    my( $x, $y, $d ) = @_;
    my $bsize = 4**($d-1);

    if( $x == $y ) {
        return $d
    }
    elsif( int( $x / 4 ) == int( $y / 4 ) ) {
        return $d-1;
    }
    elsif( int( $x / $bsize ) == int( $y / $bsize ) ) {
        return 1 + f( $x % $bsize, $y % $bsize, $d-1 );
    }
    else{
        return     f( $x % $bsize, $y % $bsize, $d-1 );
    }
}