I need help and If possible do In one file, rather than splitting and making 3 files. Has to be done in c#

LetterDemo.cs Instructions 1 using static System.Console; 2 class LetterDemo Create an application class named LetterDemo that instantiates objects of two classes named Letter and CertifiedLetter and that demonstrates all their methods 4 static void Main() 6 II Write your code here The classes are used by a company to keep track of letters they mail to clients. The Letter class includes auto-implemented properties for the Name of the recipient and the Date mailed (stored as strings) 10// Write your classes here Next Step Instructions Run Code Test Grade