func_code_string: #include <bits/stdc++.h>   using namespace std;   const int INF = 123456789;   template <class T>   void scanint(T& x) {     register int c = getchar();     x = 0;     int m = 0;     if (c ==  - ) {       m = 1;     }     for (; (c < 48 || c > 57); c = getchar())       ;     for (; c > 47 && c < 58; c = getchar()) {       x = (x << 1) + (x << 3) + c - 48;     }     if (m == 1) {       x *= -1;     }   }   template <typename T>   void cinall(T& t) {     cin >> t;   }   template <typename T, typename... Args>   void cinall(T& t, Args&... args) {     cin >> t;     cinall(args...);   }   int main() {     ios_base::sync_with_stdio(false);     int n;     cinall(n);     ;     vector<int> v(n);     vector<int> xv(n + 1);     long long sol = 0;     for (int i = 0; i < n; ++i) {       cin >> v[i];       sol ^= v[i];       xv[i + 1] = xv[i] ^ i;     }     for (int i = 2; i <= n; ++i) {       sol ^= xv[((n / i) % 2) * i] ^ xv[(n % i) + 1];     }     cout << sol;     return 0;   }   