DO YOU EXPECT ME TO FIND THIS OUT?

WHAT BASE AND/XOR LANGUAGE INCLUDES string?

DON'T BYTE OF MORE THAN YOU CAN CHEW

YOU CAN ONLY DISTORT THE LARGEST OF MATHEMATICS SO FAR

SAYING "ABRACADABRA" WITHOUT A MAGIC AND WON'T DO YOU ANY GOOD

THE LAST STACK RUPTURES. ALL DIE. OH, THE EMBARRASSMENT!

I HAVE NO ARRAY AND I MUST SCREAM

ELEMENTS MAY NOT BE STORED IN WEST HYPERSPACE

Input

The first line of input data contains a single integer n (1 ≤ n ≤ 10).

The second line of input data contains n space-separated integers ai (1 ≤ ai ≤ 11).

Output

Output a single integer.

Example

Input

4
2 5 3 1


Output

4
#include <bits/stdc++.h>
using namespace std;
const int maxn = 100005;
const long long mod = 1e9 + 7;
const long long INF = 1e18;
const double eps = 1e-6;
int n, x;
int main() {
  scanf("%d", &n);
  int Max = 0, la = 0;
  for (int i = 0; i < n; i++) {
    scanf("%d", &x);
    la = x;
    Max = max(Max, x);
  }
  printf("%d\n", Max ^ la);
}
