func_code_string: #include <bits/stdc++.h>   using namespace std;   const long long mod = 1e9 + 7;   const int maxn = 1e5 + 10;   int main() {     ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);     int n;     cin >> n;     vector<int> a(n);     for (int i = 0; i < n; ++i) cin >> a[i];     int ans = 0;     vector<int> b(n);     for (int k = 0; k < 26; ++k) {       for (int i = 0, mod = (1 << (k + 1)); i < n; ++i) b[i] = a[i] % mod;       sort(b.begin(), b.end());       long long cnt = 0;       int l1 = (1 << k), r1 = (1 << (k + 1)) - 1;       int l2 = (1 << (k + 1)) + (1 << k), r2 = (1 << (k + 2)) - 2;       for (int i = 0; i < n; ++i) {         int l = l1 - b[i], r = r1 - b[i];         cnt += upper_bound(b.begin(), b.begin() + i, r) -                lower_bound(b.begin(), b.begin() + i, l);       }       for (int i = 0; i < n; ++i) {         int l = l2 - b[i], r = r2 - b[i];         cnt += upper_bound(b.begin(), b.begin() + i, r) -                lower_bound(b.begin(), b.begin() + i, l);       }       if (cnt & 1) ans += (1 << k);     }     cout << ans << endl;     return 0;   }   