#include <bits/stdc++.h>
using namespace std;
struct cww{cww(){ios::sync_with_stdio(false);cin.tie(0);}}star;
int main()
{	
	int N;
	cin >> N;
	if ( N % 2 == 1 ){
		cout << N + 1 << endl;
	}else{
		cout << N << endl;
	}
	return 0;
}