#!/usr/bin/perl
use warnings;
use strict;
use 5.010;

# The 3n + 1 problem (http://www.streamtech.nl/problemset/100.html)

my ( $first, $second, $cycle_length );
my $max_cycle_length = 0;

say "Input:";
chomp( my @pairs = <> );

say "Output:";
foreach my $pair (@pairs) {
    ( $first, $second ) = split( / /, $pair );

    foreach my $num ( $first .. $second ) {
        $cycle_length = totalizer($num);
        if ( $cycle_length > $max_cycle_length ) {
            $max_cycle_length = $cycle_length;
        }
    }
    say "$first $second $max_cycle_length";
}

sub totalizer {
    my $number = shift;
    $cycle_length = 0;
    {
        ++$cycle_length;
        last if ( $number == 1 );

        if ( $number % 2 != 0 ) {
            $number = ( $number * 3 + 1 );
        }
        else {
            $number = $number / 2;
        }
        redo;
    }
    return $cycle_length;
}