import sys 
lamda = [4] * 13
xmaxUser1021 = [0,0,0,0,0,0,0,0,0,0,0,0,0]
surplusEnergyUser1021 = [4.047,0,0,0,0,0,0,0,0,0,0,0,0]
lamdaUser1021 = lamda
pricesUser1021 = [9.0,0,0,0,0,0,0,0,0,0,0,0,0]
p = float(sys.argv[1])
t = int(sys.argv[2])
x = (pricesUser1021[t] - p)/lamdaUser1021[t]
if x < 0:
	x = 0
elif x > xmaxUser1021:
	x = xmaxUser1021
print(str(x))
sys.stdout.flush()