use strict;

while (<DATA>) {
	chomp;
	print "$_: ", compare(split / /, $_), " in common.\n"
}

sub compare {
	my ($word1, $word2) = @_;
	my $n = length($word2);
	$word2 =~ s/$_// foreach split //, $word1;
	return $n - length($word2)
}

__DATA__
perl monk
help temp
frood hoopy
bilbo baggins
jibber jaber
aabcc abbbc