using System;
public class Program
{
public static void Main()
var b = new B(1, 2);
var c = new C(3, 4);
Console.WriteLine(b.x +" : "+c.x);
}
public class A
public int x;
public A(int x)
this.x = x;
public class B : A
private int y;
public B(int x, int y) : base(x)
this.y = y;
public class C : A
private int z;
public C(int x, int z) : base(x)
this.z = z;