sub combinations {
#58+58=116
#23456789_123456789_123456789_123456789_123456789_123456789_
my@a;$;=@{$_[0]}**@_;while($a=pop){$==0;for$a((@$a)x($;>>(  
$b=@$a**@_)||1)){push@{$a[$=++]},$a for+1..$b}}@a[0..$;-1]
}