import java.util.Scanner;


public class Main_yukicoder192 {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        int n = sc.nextInt();

        if (n % 2 == 0) {
        	System.out.println(n);
        } else {
        	System.out.println(n + 1);
        }
        
        sc.close();
    }
}