#include <bits/stdc++.h>
using namespace std;
#define EMT ios::sync_with_stdio(0); cin.tie(0);
using ll = int64_t;
using ull = uint64_t;
using uint = uint32_t;
using ld = long double;
const int INF = 0x3f3f3f3f;
const int MOD = 1e9 + 7;
const ll LINF = 1e18;
const double EPS = 1e-9;
const int N = 4e3 + 25;
int cnt[N];
signed main() {
int n;
cin >> n;
vector<int> arr(n);
for(int i = 0; i < n; i++)
cin >> arr[i], cnt[arr[i]]++;
int ans = 0;
for(int i = 0; i < N; i++) {
for(int j = i + 1; j < N; j++)
if((cnt[i] & 1) && (cnt[j] & 1))
ans ^= i + j;
if((1LL * cnt[i] * (cnt[i] + 1) / 2) & 1)
ans ^= i + i;
}
cout << ans << '\n';
}
