Python exercise: Pizza Cost Calculator

Today's exercise is to work out a cost calculator for a pizza order. This exercise uses if, elif, else, and changing the cost variable as items are added to the order.

My initial take on the exercise gave me the result I was looking for:

Welcome to Python Pizza Deliveries!
What size pizza do you want? S, M, or L: L
Do you want pepperoni? Y or N: Y
Do you want extra cheese? Y or N: Y
Your final bill is: $29.

size = input("What size pizza do you want? S, M, or L ")
add_pepperoni = input("Do you want pepperoni? Y or N ")
extra_cheese = input("Do you want extra cheese? Y or N ")

if size == "S": 
    bill = 15 
    if add_pepperoni == "Y": 
        bill += 2 
    if extra_cheese == "Y": 
        bill += 1 
        print(f"Your final bill is: ${bill}.")
    else: print(f"Your final bill is: ${bill}.")

if size == "M": 
    bill = 20 
    if add_pepperoni == "Y": 
        bill += 3 
    if extra_cheese == "Y": 
        bill += 1 
        print(f"Your final bill is: ${bill}.") 
    else: print(f"Your final bill is: ${bill}.")

if size == "L": 
    bill = 25 
    if add_pepperoni == "Y": 
        bill += 3 
    if extra_cheese == "Y": 
        bill += 1 
        print(f"Your final bill is: ${bill}.") 
    else: print(f"Your final bill is: ${bill}.")

But, after viewing the instructor's version (see below), I saw that my code was a bit more inefficient, and I also could've made better use of "else," instead of spelling out each separate option. My solution was 27 lines, vs. their 18 lines.

size = input("What size pizza do you want? S, M, or L ")
add_pepperoni = input("Do you want pepperoni? Y or N ")
extra_cheese = input("Do you want extra cheese? Y or N ")

bill = 0
if size == "S":
    bill += 15
 if size == "M":
    bill += 20
 if size == "L":
    bill += 25

if add_pepperoni == "Y":
    if size == "S":
        bill += 2
    else:
        bill += 3

if extra_cheese == "Y":
    bill += 1

print(f"Your final bill is: ${bill}.")

Keep practicing!