/**
* author: a.k
* created: idk
**/
#include <bits/stdc++.h>
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
#pragma GCC target("avx,avx2,fma")
using namespace std;
#define all(x) x.begin(), x.end()
#define pb push_back
#define nl '\n'
const int N = 4e3 + 1;
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
int n; cin >> n;
vector<int> a(n);
for(auto &u : a) cin >> u;
int res = 0;
for(int i = 0; i < n; i++) {
for(int j = i; j < n; j++) {
res ^= (a[i] + a[j]);
}
}
cout << res << nl;
}
