#include <bits/stdc++.h>
using namespace std;
const long long LINF = LLONG_MAX;
const int INF = INT_MAX;
const int MOD = 998244353;
int main() {
  ios::sync_with_stdio(false);
  cin.tie();
  int n;
  cin >> n;
  cout << (n + (n & 1));
}
