http://gdutcode.sinaapp.com/problem.php?id=1160
http://acm.hdu.edu.cn/showproblem.php?pid=4479
35 51 2 12 3 23 4 31 4 44 5 45 51 2 22 3 33 4 41 4 54 5 55 51 2 22 3 33 4 41 4 54 5 6