#!/usr/bin/perl

sub c {my$n=-1+shift;$n?map{my$c=$_;map$c.$_,c($n,@_)}@_:@_};
sub d {my$n=shift;--$n?map{my$d=$_;map$d.$_,d($n,@_)}@_:@_};

print join " ", c qw(2 a b c);
print "\n";
print join " ", d qw(2 a b c);
print "\n";
print join " ", c qw(4 0 1);
print "\n";
print join " ", d qw(4 0 1);
print "\n";