#include <cassert>
#include <cmath>
#include <cstdint>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <algorithm>
#include <bitset>
#include <complex>
#include <deque>
#include <functional>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>

using namespace std;

using Int = long long;

template <class T1, class T2> ostream &operator<<(ostream &os, const pair<T1, T2> &a) { return os << "(" << a.first << ", " << a.second << ")"; };
template <class T> void pv(T a, T b) { for (T i = a; i != b; ++i) cerr << *i << " "; cerr << endl; }
template <class T> bool chmin(T &t, const T &f) { if (t > f) { t = f; return true; } return false; }
template <class T> bool chmax(T &t, const T &f) { if (t < f) { t = f; return true; } return false; }


constexpr int LIM = 4'000'010;
bitset<LIM> bs;

int N;
vector<int> A;

int main() {
  for (; ~scanf("%d", &N); ) {
    A.resize(N);
    for (int i = 0; i < N; ++i) {
      scanf("%d", &A[i]);
    }
    
    bs.reset();
    bs[0] = 1;
    for (int i = 0; i < N; ++i) {
      bs ^= bs << A[i];
    }
    
    int ans = 0;
    for (int x = 1; x < LIM; ++x) if (bs[x]) {
      ans ^= x;
    }
    
    printf("%d\n", ans);
  }
  return 0;
}