import sys 
lamda = [4] * 13
xmaxUser1034 = [0,0,0,0,0,0,0,0,0,0,0,0,0]
surplusEnergyUser1034 = [2.119,0,0,0,0,0,0,0,0,0,0,0,0]
lamdaUser1034 = lamda
pricesUser1034 = [5.7,0,0,0,0,0,0,0,0,0,0,0,0]
p = float(sys.argv[1])
t = int(sys.argv[2])
x = (pricesUser1034[t] - p)/lamdaUser1034[t]
if x < 0:
	x = 0
elif x > xmaxUser1034:
	x = xmaxUser1034
print(str(x))
sys.stdout.flush()