#include <iostream>
using namespace std;
typedef unsigned int uint;
int main() {
unsigned int a, size;
cin >> a;
size = a;
uint b[a];
for (unsigned int i = 0; i < a; ++i) {
cin >> b[i];
}
//--------------------------------------------
a = b[1];
for(uint i = 1; i < size; i++) {
for(uint j = i+1; j < size;j++) {
a ^= b[j];
}
}
a += 1;
cout << a << endl;
return 0;
}