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;
long long power(long long b, long long e, long long m) {
  long long p = 1;
  while (e > 0) {
    if (e & 1) p = (p * b) % m;
    e = e >> 1;
    b = (b * b) % m;
  }
  return p;
}
long long a[11];
int main() {
  long long n, i = 0, j, m, h, h1, h2, q, k, l, r, ans;
  scanf("%lld", &n);
  for (i = 0; i < n; i++) {
    scanf("%lld", &a[i]);
  };
  printf("%lld\n", a[n - 1] ^ a[max_element(a, a + n) - a]);
  return 0;
}
