using System;

​

enum OneOrThree

{

    One = 1,

    Three = 3,

    Both = 4

}

​

public class Program

{

    public static void Main()

    {

        // All good

        doSomething(OneOrThree.One);

        // Also fine

        var both = (OneOrThree)4;

        doSomething(both);

        // Outputs 5

        var bad = (OneOrThree)5;

        doSomething(bad);

    }

​

    static void doSomething(OneOrThree arg)

    {

        Console.WriteLine(arg);

    }

}