import sys 
lamda = [4] * 13
xmaxUser1036 = [0,0,0,0,0,0,0,0,0,0,0,0,0]
surplusEnergyUser1036 = [0.943,0,0,0,0,0,0,0,0,0,0,0,0]
lamdaUser1036 = lamda
pricesUser1036 = [7.4,0,0,0,0,0,0,0,0,0,0,0,0]
p = float(sys.argv[1])
t = int(sys.argv[2])
x = (pricesUser1036[t] - p)/lamdaUser1036[t]
if x < 0:
	x = 0
elif x > xmaxUser1036:
	x = xmaxUser1036
print(str(x))
sys.stdout.flush()