99 - ZOJ Monthly, November 2010 - F
Alice bought a lot of pairs of socks yesterday. But when she went home, she found that she has lost one of them. Each sock has a name which contains exactly 7 charaters.
Alice wants to know which sock she has lost. Maybe you can help her.
There are multiple cases. The first line containing an integer n (1 <= n <= 1000000) indicates that Alice bought n pairs of socks. For the following 2*n-1 lines, each line is a string with 7 charaters indicating the name of the socks that Alice took back.
The name of the lost sock.
2 aabcdef bzyxwvu bzyxwvu 4 aqwerty eas fgh aqwerty easdfgh easdfgh aqwerty aqwerty 2 0x0abcd 0ABCDEF 0x0abcd
aabcdef eas fgh 0ABCDEF
Because of HUGE input, scanf is recommended.
Author: LIANG, Jiaxing
Contest: ZOJ Monthly, November 2010