Using arrays C#

Write a program named PizzaPrices that prompts the user to make a choice for a pizza size - S,M, L, or X - and the number of pizza the user wants to order. The price for different size pizzas are $6.99, $8.99, $12.5, and $15.0 respectively. There is also a discount based on the number of pizza ordered: no discount for one pizza, 10% discount for 2 pizzas, 15% discount for 3-5 pizzas, and 20% for more than 5 pizzas. Display a full accounting of the transaction.