$| = 1;
$i = 1;
while (1) {
	if (isprime($i)) {
		$p = 1;
		for ($j = 1; $j <= length($i); $j++) {
			if ($i !~ $j) {
				$p = 0;
				last;
			}
		}
		if ($p) {
			print "F: $i\n";
		}
	}
	$i += 2;
}
exit;

sub isprime {
    my $num = $_[0];
    my $val = 'prime';
    if ($num =~ /^\d+$/ && $num >= 2) {
        my $mod = 2;
        my $div = int sqrt $num;
        while ($mod <= $div) {
            ($num % $mod) == 0 ? ($val = 'composite', last) : $mod++;
        }
    } else { $val = 'neither'; }
    if ($val eq 'prime') {
      return 1;
    } else {
      return 0;
    }
}