bike race

junior_bikers = int(input())
senior_bikers = int(input())
type_of_the_race = input()
bills = 0
total_sum = 0
final_sum = 0
discount = 0
total_bikers = senior_bikers + junior_bikers

if type_of_the_race == "trail":
    total_sum = (junior_bikers * 5.50) + (senior_bikers * 7)

elif type_of_the_race == "cross-country":
    total_sum = (junior_bikers * 8) + (senior_bikers * 9.50)
    if total_bikers >= 50:
        discount = total_sum * 0.25

elif type_of_the_race == "downhill":
    total_sum = (junior_bikers * 12.25) + (senior_bikers * 13.75)

elif type_of_the_race == "road":
    total_sum = (junior_bikers * 20) + (senior_bikers * 21.50)

total_sum_with_discount = total_sum - discount
bills = total_sum_with_discount * 0.05
final_sum = total_sum_with_discount - bills
print(f"{final_sum:.2f}")