#include <bits/stdc++.h>   using namespace std;   int main() {     long long n;     cin >> n;     if (n == 0) {       cout << 0 << endl;     } else if ((n + 1) % 2 == 0) {       cout << (n + 1) / 2 << endl;     } else {       cout << n + 1 << endl;     }     return 0;   }   