#include <bits/stdc++.h>   using namespace std;   const int N = 400005;   int n, m, k, s, t, a[N], b[N];   int ans;   long long p;   int main() {     ios::sync_with_stdio(0);     cin.tie(0);     cout.tie(0);     cin >> n;     for (int i = 1; i <= n; ++i) cin >> a[i];     for (int j = 0; j < 25; ++j) {       for (int i = 1; i <= n; ++i) p += ((a[i] >> j) & 1) * (n - 1);       if (p & 1) ans += 1 << j;       p = 0;       for (int i = 1; i <= n; ++i) b[i] = a[i] % (1 << (j + 1));       sort(b + 1, b + 1 + n);       int r = n;       for (int l = 1; l < n; ++l) {         while (r > l && b[l] + b[r] >= (1 << (j + 1))) --r;         if (r <= l) r = l;         p += n - r;       }     }     cout << ans << endl;   }   