#!/usr/bin/perl

# https://perlmonks.org/?node_id=1227147

use warnings;
use strict;

my $pattern = 'FTTF';

my @result = grep {
				$pattern =~ /(?!$)/g;
				$pattern =~ /./g;
				$& eq 'T'
				} 0 .. 12;

print "@result\n";