#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using ll = long long;
constexpr ll mod = 1e9 + 7;
constexpr ll INF = 1LL << 60;

#define REP(i, init, n) for(int i = (int)(init); i < (int)(n); i++)
#define All(A) A.begin(), A.end()
#define rAll(A) A.rbegin(), A.rend()

#define vi vector<int>
#define vl vector<long>
#define vvi vector<vector<int>>
#define vvl vector<vector<long>>
#define pint pair<int, int>
#define plong pair<long, long>

int N;
vi A;

void solve() {
    bitset<4000100> bs;
    bs.set(1);
    REP(i, 0, N) {
        bitset<4000100> bs_tmp = bs;
        bs_tmp <<= A[i];
        bs ^= bs_tmp;
    }
    int ans = 0;
    REP(i, 1, 4000010) {
        if(bs[i]) {
            ans ^= (i - 1);
        }
    }
    cout << ans << endl;
}

int main() {
    cin >> N;
    A.resize(N);
    REP(i, 0, N) cin >> A[i];
    solve();
}