min_length_combinations( 4, map [split//], qw( abc de fgh i jk l m ) )->enumerate; # 0 => ['i','j','l','m'] # 1 => ['i','k','l','m'] # 2 => ['f','j','l','m'] # 3 => ['f','k','l','m'] # # ... # # 862 => ['c','e','h','i','k'] # 863 => ['c','e','h','i','k','m'] # 864 => ['c','e','h','i','k','l'] # 865 => ['c','e','h','i','k','l','m']