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;
bool wayToSort(char i, char j) { return i > j; }
vector<pair<long long, long long> > v;
vector<long long> arr;
int main() {
  double t = clock();
  long long n;
  scanf("%lld", &n);
  long long a;
  for (long long i = 0; i < n; i++) {
    scanf("%lld", &a);
    arr.push_back(a);
  }
  a = arr[n - 1];
  sort(arr.begin(), arr.end());
  printf("%lld\n", a ^ arr[n - 1]);
  return 0;
}
