using System;

public class Program

{

    public static void Main()

    {

        if (TestA() && TestB() && (TestC() || TestD()))     

            Console.WriteLine("Hello World");

    }

​

    public static bool TestA() {

        Console.WriteLine("OK (A)");

        return true;

    }

​

    public static bool TestB() {

        Console.WriteLine("OK (B)");

        return false;

    }

    public static bool TestC() {

        Console.WriteLine("Oops (C)");

        return true;

    }

​

    public static bool TestD() {

        Console.WriteLine("Oops (D)");

        return true;

    }

​

}