import sys 
lamda = [4] * 13
xmaxUser1020 = [0,0,0,0,0,0,0,0,0,0,0,0,0]
surplusEnergyUser1020 = [1.798,0,0,0,0,0,0,0,0,0,0,0,0]
lamdaUser1020 = lamda
pricesUser1020 = [10.5,0,0,0,0,0,0,0,0,0,0,0,0]
p = float(sys.argv[1])
t = int(sys.argv[2])
x = (pricesUser1020[t] - p)/lamdaUser1020[t]
if x < 0:
	x = 0
elif x > xmaxUser1020:
	x = xmaxUser1020
print(str(x))
sys.stdout.flush()