#include <bits/stdc++.h>
using namespace std;
const int mxN = 4e6 +5;
int main(){
    int n;
    cin >> n;
    bitset <mxN> dp;
    dp[0] = 1;
    for(int i = 0, a;i < n;i++){
        cin >> a;
        dp ^= (dp << a);
    }

    int ans = 0;
    for(int i = 0;i < mxN;i++)
        if(dp[i]) ans ^= i;

    cout << ans << "\n";

    return 0;
}