import java.util.Scanner;
public class Gousei{
	public static void main(String arg[]){
		int n,res;
		Scanner sc = new Scanner(System.in);
		n = sc.nextInt();
		if(n % 2 == 0){
			res = n;
		}else{
			res = n + 1;
		}
		System.out.println(res);
	}
}