fruit

fruit, day, quantity = input(), input(), float(input())
total_price = 0
days_prices = {'days': [['Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday'], ['Saturday', 'Sunday']],
               'prices': {"banana": [2.5, 2.7], 'apple': [1.2, 1.25], 'kiwi': [2.7, 3], 'orange': [0.85, 0.9],
                          'grapefruit': [1.45, 1.6], 'pineapple': [5.5, 5.6], 'grapes': [3.85, 4.2]}}

if fruit in days_prices['prices'] and day in days_prices['days'][0]:
    total_price = quantity * days_prices['prices'][fruit][0]
elif fruit in days_prices['prices'] and day in days_prices['days'][1]:
    total_price = quantity * days_prices['prices'][fruit][1]

if total_price == 0:
    print('error')
else:
    print(f'{total_price:.2f}')