using System;

public class Program

{

    public static void Main()

    {

        var StrWithMathExpression = $"1 + 2 = {1 + 2}"; // -> "1 + 2 = 3"

        Console.WriteLine(StrWithMathExpression);

        string world = "world";

        var StrWithFunctionCall = $"Hello, {world.ToUpper()}!"; // -> "Hello, WORLD!"

        Console.WriteLine(StrWithFunctionCall);

    }

}