#include <bits/stdc++.h>
using namespace std;
#define chmax(a, b) a = (((a)<(b)) ? (b) : (a))
#define chmin(a, b) a = (((a)>(b)) ? (b) : (a))
int main(){
  int N;
  cin >> N;
  assert(0 <= N && N <= 1e8);
  if (N % 2 == 0) N++;
  cout << N << endl;
}