fruit = input().lower()
day = input().lower()
itemNumber = float(input())
result = 0.0

validFruit = fruit == "banana" or fruit == "apple" or fruit == "orange" or fruit == "grapefruit" or fruit == "kiwi" or fruit == "pineapple" or fruit == "grapes"
validDay = day == "Monday" or day == "Tuesday" or day == "Wednesday" or day == "Thursday" or day == "Friday" or day == "Saturday" or day == "Sunday "
if not validDay or not validFruit:
    print("error")
else:
    if day == "Saturday" or day == "Sunday":
        if fruit == "banana":
            result = itemNumber * 2.70
        elif fruit == "apple":
            result = itemNumber * 1.25
        elif fruit == "orange":
            result = itemNumber * 0.90
        elif fruit == "grapefruit":
            result = itemNumber * 1.60
        elif fruit == "kiwi":
            result = itemNumber * 3.00
        elif fruit == "pineapple":
            result = itemNumber * 5.60
        elif fruit == "grapes":
            result = itemNumber * 4.20
    elif day == "Monday" or day == "Tuesday" or day == "Wednesday" or day == "Thursday" or day == "Friday":
        if fruit == "banana":
            result = itemNumber * 2.50
        elif fruit == "apple":
            result = itemNumber * 1.20
        elif fruit == "orange":
            result = itemNumber * 0.85
        elif fruit == "grapefruit":
            result = itemNumber * 1.45
        elif fruit == "kiwi":
            result = itemNumber * 2.70
        elif fruit == "pineapple":
            result = itemNumber * 5.50
        elif fruit == "grapes":
            result = itemNumber * 3.85
    print(f"{result:.2f}")