bike race

number_junior_bikers = int(input())
number_senior_bikers = int(input())
type_of_race = input()
junior_price = 0
senior_price = 0

if type_of_race == 'trail':
    junior_price = 5.50
    senior_price = 7
elif type_of_race == 'cross-country':
    junior_price = 8
    senior_price = 9.50
    if number_junior_bikers + number_senior_bikers >= 50:
        junior_price *= 0.75
        senior_price *= 0.75
elif type_of_race == 'downhill':
    junior_price = 12.25
    senior_price = 13.75
elif type_of_race == 'road':
    junior_price = 20
    senior_price = 21.50

total_price = number_junior_bikers * junior_price + number_senior_bikers * senior_price
after_tax = total_price - total_price * 0.05

print(f'{after_tax:.2f}')