use strict;
use warnings;

$\="\n";
$|=1;

redos($_) for 5..8;


sub redos {
    my ($length)=@_;


    my $futile = 'a' x $length;

    print "=== length=$length string=$futile";
    print 'start     ', my $start = scalar time;
    die 'huh?' if $futile =~
      /a*a*a*a*a*a*a*a*a*a*a*a*a*a*a*a*a*a*a*a*a*a*a*a*a*a*a*a*a*a*a*a*a*a*[bc]/
        ;
    print 'post rx 1 ',  time -$start," sec";
    die 'huh?' if $futile =~
      /(?:(?:(?:(?:(?:(?:(?:(?:(?:(?:(?:(?:(?:a*)*)*)*)*)*)*)*)*)*)*)*)*)*[bc]/
        ;
    print 'post rx 2 ',  time -$start," sec";
    print 'done      ',  time -$start," sec";
    print "\n" x2;
}