题解 | #网购#

price, month, day, has_coupon = input().split()


if month+day == "1111":
    discount = 0.7
else :
    discount = 0.8

if(has_coupon == "1"):
    cut = 50
else:
    cut = 0

cost = float(price)*discount - cut

print("%.2f" %(cost if cost >= 0 else 0.00))