using System;
class MyClass {
public int x;
}
class MainClass {
public static void Main() {
MyClass a = new MyClass();
MyClass b = new MyClass();
a.x = 10;
b.x = 20;
Console.WriteLine("a.x {0}, b.x {1}", a.x, b.x);
a = b;
b.x = 30;
Console.WriteLine("a.x {0}, b.x {1}", a.x, b.x);
}
}