using System;

public class Program

{

    public record A(string Prop1, string Prop2);

    //public record B(string Prop3) : A; //error

    public record C(string Prop1, string Prop2, string Prop3) : A(Prop1, Prop2);

    public static void Main()

    {

        var a1 = new A("1", "2");

        Console.WriteLine(a1);

        /*

        var a2 = new A //error

        {

            Prop1 = "1",

            Prop2 = "2",

        };

        */

        var c = new C("1", "2", "3");   

        Console.WriteLine(c);

    }

}