using System;

public class Program

{

    public static void Main()

    {

            int x = 1, y = 2, z = x + y;

            float a = 5, b = 3;

            double c = a / b;

​

            Console.WriteLine("Hello world");

            Console.WriteLine($"{x} + {y} = {z}");

            Console.WriteLine("{0} / {1} = {2}", a, b, c);

    }

}