Donald is a postman
题目链接：
http://acm.hust.edu.cn/vjudge/contest/126546#problem/L
Description
Donald Duck works as a postman for the Walt Disney Studios. He delivers children’s
letters from all over the world to his friends, which are cartoon characters. The Studios
has three cases for the letters, with nine sections in each case. Every section has the name of the receiver
on it. All cases stand in a row as it is shown at the picture below.
Donald Duck have brought