using System;

public class Program

{

    public static void Main()

    {

        Say.hi();

        double d=Code.pi();

        Console.WriteLine(d);

        Sum.add(20,20);

        int e = Add.sub(40,20);

        Console.WriteLine(e);

    }

}

​

//no input & no output

public class Say

{

  public static void hi()

  {

   Console.WriteLine("Hello to all");

  }

}

​

//no input & with output

public class Code

{

  public static double pi()

  {

   return 3.14;

  }

}

​

//with input & no output

public class Sum

{

 public static void add(int a ,int b)

 {

  int z=a+b;

    Console.WriteLine(z);

 }

}

​

//with input & with output

public class Add

{ 

   public static int sub(int x ,int y)

   {

    int c = x-y;

       return c;

   }

}

​