def discount(price, isDiscount):
    if isDiscount:
        price -= 50
    return price if price > 0 else 0    
while True:
    try:
        price, month, day, isDiscount = map(float, input().split())
        result = price
        if month == 11 and day == 11:
            print('{:.2f}'.format(discount(result*0.7, isDiscount)))
        elif month == 12 and day == 12:
            print('{:.2f}'.format(discount(result*0.8, isDiscount)))
        else:            
            print('{:.2f}'.format(result))
    except EOFError:
        break