#include "bits/stdc++.h"
using namespace std;
#define ll long long
#define SZ(s) (int)s.size()
#define ff first
#define ss second
const int N = (4e3 + 5);
int T, n, m, vis[N+1];
signed main(){
ios::sync_with_stdio(false); cin.tie(nullptr);
cin >> n;
vector <int> a(n);
for(int i = 0; i < n; i++){
cin >> a[i];
vis[a[i]]++;
}
int ans = 0;
for(int i = 0; i < N; i++){
for(int j = 0; j < N; j++){
if(!vis[i] or !vis[j]) continue;
if((vis[i]*vis[j]) % 2) ans ^= (i+j);
}
}
cout << ans << '\n';
return 0;
}
