using System;

​

public class Program

{

    public static void Main()

    {

        Child x = new Child();

        Console.WriteLine(x.f(1));

    }

    public class Base

    {

        public virtual string f(int a){

            return "base";

        }

    }

    public class Child : Base

    {

        public override string f(int a)

        {

            return "override";

        }

        public new string f(double a){

            return "child";

        }

    }

}

​

​