#!/usr/bin/env perl

use strict;
use warnings;

my @tests = (
    [qw{ABCGE ABCGE}],
    [qw{ABCGE FGCGB}],
    [qw{ABCGE JHAGT}],
);

for my $strings (@tests) {
    my $diff = 0;

    for my $i (0 .. length($strings->[0]) - 1) {
        my @chars = map substr($strings->[$_], $i, 1), 0, 1;
        ++$diff if $chars[0] ne $chars[1];
    }

    print "@$strings $diff\n";
}

##</code><code>##

ABCGE ABCGE 0
ABCGE FGCGB 3
ABCGE JHAGT 4