c, d  =map(int, input().split())

if 3*d <= c:
    x = 4*d
    y = 0
elif 7*c < 15*d and 2*d <= 5*c:
    x = (20*c-8*d)/13
    y = (-7*c+21*d)/13
else:
    x = 0
    y = 7*c/2
print(1000*x+2000*y)