#include <stdio.h>
#include <bits/stdc++.h>
#include <atcoder/all>
using namespace atcoder;
using mint = modint998244353;
using namespace std;
#define rep(i,n) for(int i=0;i<(n);i++)
#define Inf 1000000000000000000

int main(){
	
	int n;
	cin>>n;
	
	bitset<4000001> B;
	B[0] = 1;
	rep(i,n){
		int a;
		cin>>a;
		B ^= B<<a;
	}
	
	int ans = 0;
	rep(i,B.size()){
		if(B[i])ans ^= i;
	}
	
	cout<<ans<<endl;
	
	
	return 0;
}