using System;

public class Program

{

    public static void Main()

    {

        string message1 = "Hello";

​

        string message2 = message1 + " World!!";

        Console.WriteLine(message2);

        int i = 10, j = 20;

        int sum = i + j;

        Console.WriteLine("{0} + {1} = {2}", i, j, sum);

        Console.WriteLine("{0},{1},{2}", i, j, sum);

        Console.WriteLine(i +" + "+ j+ " = "+ sum);

    }

}