use strict;
use warnings;

use Benchmark 'cmpthese';

my $sz      = ( shift || 10 ) - 4;
my $X = 'N' . 'x' x $sz . '000';
my $Y = 'N' . 'x' x $sz . '001';

print("X = $X\n");
print("Y = $Y\n");
print("\n");

cmpthese( -1, {
'/^N(?!.*00$).*$/ failure' => sub { scalar $X =~ /^N(?!.*00$).*$/ },
'/^N(?!.*00$).*$/ success' => sub { scalar $Y =~ /^N(?!.*00$).*$/ },
'/^N(?!.*00$)/    failure' => sub { scalar $X =~ /^N(?!.*00$)/    },
'/^N(?!.*00$)/    success' => sub { scalar $Y =~ /^N(?!.*00$)/    },
'/^N.*(?<!00$)$/  failure' => sub { scalar $X =~ /^N.*(?<!00$)$/  },
'/^N.*(?<!00$)$/  success' => sub { scalar $Y =~ /^N.*(?<!00$)$/  },
'/^N.*(?!00)..$/  failure' => sub { scalar $X =~ /^N.*(?!00)..$/  },
'/^N.*(?!00)..$/  success' => sub { scalar $Y =~ /^N.*(?!00)..$/  },
});