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;
using ll = long long;
using ld = double;
using pll = pair<ll, ll>;
using vll = vector<ll>;
using vpll = vector<pll>;
using vvll = vector<vll>;
ll N, A[100];
int main() {
  ios::sync_with_stdio(0);
  cout.tie(0);
  cin.tie(0);
  cin >> N;
  for (ll i = 0; i < (ll)N; ++i) cin >> A[i];
  ll m = 0;
  for (ll i = 0; i < (ll)N; ++i) m = max(A[i], m);
  cout << (m ^ A[N - 1]) << endl;
  return 0;
}
