import sys 
lamda = [4] * 13
xmaxUser1023 = [0,0,0,0,0,0,0,0,0,0,0,0,0]
surplusEnergyUser1023 = [4.691,0,0,0,0,0,0,0,0,0,0,0,0]
lamdaUser1023 = lamda
pricesUser1023 = [9.7,0,0,0,0,0,0,0,0,0,0,0,0]
p = float(sys.argv[1])
t = int(sys.argv[2])
x = (pricesUser1023[t] - p)/lamdaUser1023[t]
if x < 0:
	x = 0
elif x > xmaxUser1023:
	x = xmaxUser1023
print(str(x))
sys.stdout.flush()