import sys 
lamda = [4] * 13
xmaxUser1025 = [0,0,0,0,0,0,0,0,0,0,0,0,0]
surplusEnergyUser1025 = [1.482,0,0,0,0,0,0,0,0,0,0,0,0]
lamdaUser1025 = lamda
pricesUser1025 = [11.6,0,0,0,0,0,0,0,0,0,0,0,0]
p = float(sys.argv[1])
t = int(sys.argv[2])
x = (pricesUser1025[t] - p)/lamdaUser1025[t]
if x < 0:
	x = 0
elif x > xmaxUser1025:
	x = xmaxUser1025
print(str(x))
sys.stdout.flush()