
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. InputThere 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*n1 lines, each line is a string with 7 charaters indicating the name of the socks that Alice took back. OutputThe name of the lost sock. Sample Input2 aabcdef bzyxwvu bzyxwvu 4 aqwerty eas fgh aqwerty easdfgh easdfgh aqwerty aqwerty 2 0x0abcd 0ABCDEF 0x0abcd Sample Outputaabcdef eas fgh 0ABCDEF HintBecause of HUGE input, scanf is recommended. Author: LIANG, Jiaxing Contest: ZOJ Monthly, November 2010 