#include <bits/stdc++.h>
#define int long long
#define double long double
using namespace std;
const int MOD = 1000000007;
const int INF = 1e14;
using Graph = vector<vector<int>>;

signed main(){
  int N;
  cin >> N;
  if( N%2 == 0 ) cout << N+1 << endl;
  else cout << N << endl;
}