import sys 
lamda = [4] * 13
xmaxUser1038 = [0,0,0,0,0,0,0,0,0,0,0,0,0]
surplusEnergyUser1038 = [3.583,0,0,0,0,0,0,0,0,0,0,0,0]
lamdaUser1038 = lamda
pricesUser1038 = [5.2,0,0,0,0,0,0,0,0,0,0,0,0]
p = float(sys.argv[1])
t = int(sys.argv[2])
x = (pricesUser1038[t] - p)/lamdaUser1038[t]
if x < 0:
	x = 0
elif x > xmaxUser1038:
	x = xmaxUser1038
print(str(x))
sys.stdout.flush()