import sys 
lamda = [4] * 13
xmaxUser1032 = [0,0,0,0,0,0,0,0,0,0,0,0,0]
surplusEnergyUser1032 = [4.703,0,0,0,0,0,0,0,0,0,0,0,0]
lamdaUser1032 = lamda
pricesUser1032 = [11.4,0,0,0,0,0,0,0,0,0,0,0,0]
p = float(sys.argv[1])
t = int(sys.argv[2])
x = (pricesUser1032[t] - p)/lamdaUser1032[t]
if x < 0:
	x = 0
elif x > xmaxUser1032:
	x = xmaxUser1032
print(str(x))
sys.stdout.flush()