import sys 
lamda = [4] * 13
xmaxUser1030 = [0,0,0,0,0,0,0,0,0,0,0,0,0]
surplusEnergyUser1030 = [2.806,0,0,0,0,0,0,0,0,0,0,0,0]
lamdaUser1030 = lamda
pricesUser1030 = [10.0,0,0,0,0,0,0,0,0,0,0,0,0]
p = float(sys.argv[1])
t = int(sys.argv[2])
x = (pricesUser1030[t] - p)/lamdaUser1030[t]
if x < 0:
	x = 0
elif x > xmaxUser1030:
	x = xmaxUser1030
print(str(x))
sys.stdout.flush()