题目描述

Being unique is so important to people on Mars that even their lottery is designed in a unique way.  The rule of winning is simple: one bets on a number chosen from [1, 104].  The first one who bets on a unique number wins.  For example, if there are 7 people betting on 5 31 5 88 67 88 17, then the second one who bets on 31 wins.

输入描述:

Each input file contains one test case.  Each case contains a line which begins with a positive integer N (<=105) and then followed by N bets.  The numbers are separated by a space.

输出描述:

For each test case, print the winning number in a line.  If there is no winner, print "None" instead.

输入例子:

7 5 31 5 88 67 88 17

输出例子:

31