题目

import java.util.Scanner;
// 1:无需package
// 2: 类名必须Main, 不可修改public class Main {public static void main(String[] args) {Scanner sc = new Scanner(System.in);int n = sc.nextInt();sc.nextLine();int res = 0;for(int i=1;i<=n;i++){int m = sc.nextInt();res^=m;}System.out.println(res);sc.close();}
}