#!/usr/bin/env perl

use strict;
use warnings;
use Data::Dumper;

my ($x, $y) = split / /, <>; chomp $y;

if ($x == $y) {
  print 0;
  exit;
}

my @q;
my %vis;
push @q, [$y, $x, 1];
$vis{"$y:$x"} = 1;
push @q, [$x + $y, $x - $y, 1];
$vis{(sprintf "%d:%d",$x+$y,$x-$y)} = 1;
while (scalar @q) {
  my ($x, $y, $c) = @{shift @q};
  if ($x == $y) {
    print $c;
    exit;
  }

  my $mark = "$y:$x";
  unless (exists$vis{$mark}) {
    push @q, [$y, $x, $c + 1];
    $vis{$mark} = 1;
  }

  $mark = (sprintf "%d:%d",$x+$y,$x-$y);
  unless (exists$vis{$mark}) {
    push @q, [$x + $y, $x - $y, $c + 1];
    $vis{$mark} = 1;
  }
}

print -1