import sys 
lamda = [4] * 13
xmaxUser1037 = [0,0,0,0,0,0,0,0,0,0,0,0,0]
surplusEnergyUser1037 = [1.576,0,0,0,0,0,0,0,0,0,0,0,0]
lamdaUser1037 = lamda
pricesUser1037 = [6.4,0,0,0,0,0,0,0,0,0,0,0,0]
p = float(sys.argv[1])
t = int(sys.argv[2])
x = (pricesUser1037[t] - p)/lamdaUser1037[t]
if x < 0:
	x = 0
elif x > xmaxUser1037:
	x = xmaxUser1037
print(str(x))
sys.stdout.flush()