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 long long LINF = (long long)1e18;
const int INF = (int)1e9 + 7;
const int N = (int)1e5 + 1;
bool u[N + 5];
int n, mx, mn = 12;
int a[11];
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cin >> n;
  for (int i = 1; i <= n; ++i) {
    cin >> a[i];
    mx = max(mx, a[i]);
  }
  mx ^= a[n];
  cout << mx << "\n";
  return 0;
}
