#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define endl "\n"
#define rep(i, a, n) for (int i = a; i < n; ++i)

int main() {
    int n;
    cin >> n;

    cout << ((n % 2 == 1) ? n : n + 1) << endl;
    return 0;
}