use strict;
use warnings;
use feature 'say';
use Time::HiRes 'time';

my $n = 2**$ARGV[0];
say $n;
my $x = 'a' x ($n-1);
my $y = 'b' . $x;

my $t = time;
$x =~ s/./$&-/g;
say time - $t;

$t = time;
$y =~ s/./$&-/g;
say time - $t;

say $^V;

__END__