PAT 1041 Be Unique (20)

Being unique is so important to people on Mars that even their lotteryis designed in a unique way. The rule of winning is simple: one bets ona number chosen from [1, 10^4^]. The first one who bets on a uniquenumber wins. For example, if there are 7 people betting on 5 31 5 88 6788 17, then the second one who bets on 31 wins.

Input Specification:

Each input file contains one test case. Each case contains a line whichbegins with a positive integer N (<=10^5^) and then followed by Nbets. The numbers are separated by a space.

Output Specification:

For each test case, print the winning number in a line. If there is nowinner, print "None" instead.

Sample Input 1:

7 5 31 5 88 67 88 17

Sample Output 1:

31

Sample Input 2:

5 888 666 666 888 888

Sample Output 2:

None

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