public static void Main()
double total,price,discount,promotion;
Console.Write("Input total price :");
price = double.Parse(Console.ReadLine());
Console.Write("Do you have coupon [y/Y] :");
ch = char.Parse(Console.ReadLine());
Console.WriteLine("---------------------------------");
if (ch == 'y' || ch == 'Y')
Console.Write("How many discount <%> :");
discount = double.Parse(Console.ReadLine());
discount = discount/100*price;
total = price - discount;
Console.Write("Discount from coupon <15%> = {0:n} Baht\n",discount);
promotion = price*discount;
total = price-price*discount;
Console.Write("discount from promotin = {0:n} Baht\n",promotion);
Console.WriteLine("Net price = {0:n} Baht",total);