fruit

fruit = str(input())
day = str(input())
quantity = float(input())
total_price = 0
prices_week = {"banana": 2.5, 'apple': 1.2, 'kiwi': 2.7, 'orange': 0.85, 'grapefruit': 1.45, 'pineapple': 5.5,
               'grapes': 3.85}
prices_weekend = {"banana": 2.7, 'apple': 1.25, 'kiwi': 3, 'orange': 0.9, 'grapefruit': 1.6, 'pineapple': 5.6,
                  'grapes': 4.2}
if fruit in prices_week:
    if day.lower() in 'mondaytuesdaywednesdaythursdayfriday':
        total_price = quantity * prices_week[fruit]
    elif day.lower() in 'saturdaysunday':
        total_price = quantity * prices_weekend[fruit]

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