public static void Main()
Console.WriteLine("please select size:1. small 2. medium 3. large");
int userchoice = int.Parse(Console.ReadLine());
Console.WriteLine("you choice {0} is not valid ",userchoice);
Console.WriteLine("Do you need one more coffee - yes or no ?");
string userdecision = Console.ReadLine();
switch(userdecision.ToUpper())
Console.WriteLine("you desicion {0} is invalide.please try again..",userdecision);
Console.WriteLine("Thank you for shopping with us.");
Console.WriteLine("your total bill is = {0}$",coffeecost);