my $line_length = 60;
my @strings = ($genome1, $mismatches, $genome2);

# Determine the longest string of the group
my $length = (reverse sort { $a <=> $b } map { length } @strings)[0];

# Then iterate through
for (my $x = 0; $x < $length; $x += $line_length)
{
     print substr ($strings[$_], $x, $line_length),$/ for (0..2);
}