distance,time=input().split()
distance,time=int(distance),int(time)
if distance>10:
    fee=6+(10-2)*1.8+(distance-10)*1.8*1.5
else :
    if distance>2:
        fee=6+(distance-2)*1.8
    else:
        fee=6
fee+=time//3
if fee==int(fee):
            print(int(fee))
else:
            print("%.1f"%fee)