import sys 
lamda = [4] * 13
xmaxUser1035 = [0,0,0,0,0,0,0,0,0,0,0,0,0]
surplusEnergyUser1035 = [2.547,0,0,0,0,0,0,0,0,0,0,0,0]
lamdaUser1035 = lamda
pricesUser1035 = [9.8,0,0,0,0,0,0,0,0,0,0,0,0]
p = float(sys.argv[1])
t = int(sys.argv[2])
x = (pricesUser1035[t] - p)/lamdaUser1035[t]
if x < 0:
	x = 0
elif x > xmaxUser1035:
	x = xmaxUser1035
print(str(x))
sys.stdout.flush()