using System;
using System.Collections.Generic;
using static System.Console;
namespace ConsoleApp
{
    class Program
    {
        static void Main(string[] args)
        {
            ulong N = ulong.Parse(ReadLine());
            if(N % 2 == 0)
            {
                WriteLine(N / 2);
            }
            else
            {
                WriteLine(N);
            }
        }
    }
}