using System;

​

public class A{

    private int field;

    public void B(A a){

        a.field = 1;

    }

    public void PrintField(){

        Console.WriteLine(field);

    }

}

​

​

public class Program

{

    public static void Main()

    {

        A a = new A();

        A b = new A();

        a.B(b);

        b.PrintField();

    }

}