#include <bits/stdc++.h>
using namespace std;
#define pb push_back
#define in insert
#define lb lower_bound
#define F first
#define S second
#define sz size()
#define int long long
#define all(v) v.begin(),v.end()
#define FOR1(x, n) for(int j = x; j <= n; j ++)
#define FOR(x, n, m, d) for(int x = n; x <= m; x += d)
#define FORR(x, n, m, d) for(int x = n; x >= m; x -= d)
#define nikita ios_base::sync_with_stdio(0), cin.tie(0);
const int N = 1e6+5;
int a[N], b[N], pref[N], dp[N];
int n,m,k,sum=0,x,y, ans, r, cnt, l, mod = 1e9+7, mt[N];
bool used[N];
vector<int>g[N];
string s, str;
map<int, int>mp;
void solve(){
cin >> n;
FOR(i, 1, n, 1){
cin >> a[i];
}
ans = 0;
set<int>st;
FOR(i, 1, n, 1){
b[a[i]]++;
st.in(a[i]);
for(auto j : st){
if(b[j] % 2)ans ^= (a[i] + j);
}
}
cout << ans;
}
signed main(){
nikita
int tt = 1;
if(!tt)cin >> tt;
FOR(i, 1, tt, 1)solve();
}
