using System.Numerics;

public class Program
{
    public static void Main()
    {

        int num = int.Parse(Console.ReadLine() ?? string.Empty);
        //string[] str = (Console.ReadLine() ?? string.Empty).Trim().Split(' ');
        //string str = Console.ReadLine() ?? string.Empty;

        if (num % 2 == 0)
        {
            Console.WriteLine(num + 1);
        }
        else
        {
            Console.WriteLine(num);
        }
    }
}