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 double PI = acos(-1);
const long double golden = (1 + sqrt(5)) * 0.5;
int v[] = {0,   4,   22,  27,  58,  85,  94,  121, 166, 202, 265,
           274, 319, 346, 355, 378, 382, 391, 438, 454, 483, 517,
           526, 535, 562, 576, 588, 627, 634, 636, 645, 648, 654};
int main() {
  int n;
  cin >> n;
  int ans, x;
  int maximo = INT_MIN;
  for (int i = 1; i < n; i++) {
    cin >> x;
    maximo = max(maximo, x);
  }
  cin >> x;
  maximo = max(maximo, x);
  cout << (int)(x ^ maximo) << endl;
  return 0;
}
