#include <bits/stdc++.h>
using namespace std;

const int MAX_SUM = 2000 * 2000 + 1;

bitset<MAX_SUM> mask;

int main() {
    int N;
    cin >> N;
    vector<int> A(N);
    for (auto &a : A) cin >> a;

    mask.reset();
    mask.set(0); // Initialize with sum 0 (empty subset)
    for (auto a : A) {
        mask ^= mask << a;
    }

    mask.set(0, false); // Exclude the empty subset

    int res = 0;
    for (int i = 0; i < MAX_SUM; ++i) {
        if (mask[i]) res ^= i;
    }
    cout << res << endl;

    return 0;
}