# Functions go here
def string_check(question, valid_ans_list, num_letters):
    """Checks that users enter the full word
    or the first letter of a word from alist of valid responses"""

    while True:
        response = input(question).lower()

        for item in valid_ans_list:

            # check if the response is the entire word
            if response == item:
                return item

            # check if it's the 'n' letter
            elif response == item[:num_letters]:
                return item

        print(f"Please choose an option from {valid_ans_list}")

# Main routine goes here
yes_no_list = ['yes', 'no']
payment_list = ['cash', 'credit']


like_coffee = string_check("Do you like coffee? ",
                           yes_no_list, 1)
print(f"You chose {like_coffee}")
pay_method = string_check("Payment method: ", payment_list, 2)
print(f"You chose {pay_method}")



cost = int(input('Enter a number between 4 and 6'))
if pay_method == 'credit':
    charge = (cost * 2.5) /100
    cost_charge = round(cost + charge, 2 )
    print(f" Surcharge = ${charge} Total cost = ${cost_charge}" )
else:
    print(f" Total cost = ${cost}")