Find the missing tile you are waiting for to Mahjong.
$ python3 machi.py 3334567
[2] [234 567 33]
[4] [333 567 44]
[5] [345 567 33]
[7] [333 456 77]
[8] [345 678 33]
You're waiting for: [2, 4, 5, 7, 8]
Test cases: http://arcturus.su/wiki/Complex_waits