#include <bits/stdc++.h>
#define rep(i,s,n) for (int i = s; i < (n); ++i)
using namespace std;
using ll = long long;
using P = pair<int,int>;
using field = vector<vector<int>>;

int main() {
  ll n;
  cin >> n;
  if (n % 2 == 0) n++;
  cout << n << endl;
  return 0;
}