HDOJ 1563 Find your present!

import java.util.Scanner;

public class Main{
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
while (sc.hasNext()) {
int n = sc.nextInt();
if (n==0) {
break;
}
int num = sc.nextInt();
n--;
while (n-->0) {
num = num^sc.nextInt();
}
System.out.println(num);
}
sc.close();
}
}