PAT

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.

Input Specification:

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.

Output Specification:

For each test case, print the winning number in a line. If there is no winner, 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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#include<cstdio>#include<algorithm>using namespace std;int table[100001];int a[100001];int n;int main(){fill(table, table+100001, 0);scanf("%d", &n);for(int i = 0; i < n; i++){scanf("%d", &a[i]);table[a[i]]++;}int flag = 0;for(int i = 0; i < n; i++){if(table[a[i]] == 1){printf("%d\n", a[i]);flag = 1;break;}}if(!flag) printf("None\n");return 0;}