题解 | #网购#

a,b,c,d=map(str,input().split(' '))
a1=float(a)
b1=int(b)
c1=int(c)
d1=int(d)
if b1==11 and c1==11:
    a1=a1*0.7
    if d1==1:
        a1=a1-50
        if a1<0:
            a1=0
elif b1==12 and c1==12:
    a1=a1*0.8
    if d1==1:
        a1=a1-50
        if a1<0:
            a1=0
else:
    a1=a1
print('{:.2f}'.format(a1))