Sicily 1200. Stick

看穿了其实就是异或而已

// Problem#: 1200// Author#: Reid Chan#include <iostream>using namespace std;int main() {    int n;    while (cin >> n && n != 0) {        int result = 0;        int in;        for (int i = 0; i < n; ++i) {            cin >> in;            result ^= in;        }        cout << result << endl;    }    return 0;}