Besides the typical 4 sets and a pair needed to
complete a hand, 2 other variations exist :
A hand containing 7 different pairs. You cannot
have 2 of the same pairs in this hand or a Kong for that
hand, you need to have each of the 4 wind tiles and each of
the 3 dragon tiles. You also need a 1 and a 9 from each
of the 3 different suits: bamboo, dots, and characters. The last tile can be any tile stated above, making a pair.