use strict;
use warnings;

my %adj = (
	1 => [2,5,6],
	2 => [1,3,5,6,7],
	3 => [2,4,6,7,8],
	4 => [3,7,8],
	5 => [1,2,6,9,10],
	6 => [1,2,3,5,7,9,10,11],
	7 => [2,3,4,6,8,10,11,12],
	8 => [3,4,7,11,12],
	9 => [5,6,10,13,14],
	10 => [5,6,7,9,11,13,14,15],
	11 => [6,7,8,10,12,14,15,16],
	12 => [7,8,11,15,16],
	13 => [9,10,14],
	14 => [9,10,11,13,15],
	15 => [10,11,12,14,16],
	16 => [11,12,15]
);

sub boggle {
	my ($sofar, $last, $remains, $lentogo) = @_;
	return print "@$sofar\n" unless $lentogo;
	return () unless @$remains;
	my (@right, @left) = @$remains;
	while (my $next = shift @right) {
		boggle([@$sofar, $next], $next, [@left, @right], $lentogo-1) if grep {$next==$_} @{$adj{$last}};
		push(@left, $next);
	}
}

for my $len (3 .. 6) {	# len 3 .. 6
	for my $start (1 .. 16) {	# all starting points
		boggle([$start],$start,[1..$start-1,$start+1..16], $len);
	}
};