import java.util.Scanner; public class Main { /*方法1:a^a=0 a^0=a 异或满***换律 * */ public static int printOdd1(int[] arr) { int e0 = 0; for (int cur : arr) { e0 ^= cur; } return e0; } public static void main(String[] args) { Scanner in=new Scanner(System.in); int n=in.nextInt(); int[] arr=new int[n]; for (int i = 0; i <n ; i++) { arr[i]=in.nextInt(); } int res= printOdd1(arr); System.out.println(res); } }