c,d = gets.split.map(&:to_i)
c = Rational(c)
d = Rational(d)


a = Rational(20,13)*c - Rational(8,13)*d
b = -Rational(7,13)*c + Rational(21,13)*d

x = (a<0 || b<0) ? 0 : a+2*b

p ([[Rational(3,4)*c,Rational(1,4)*d].min,[Rational(2,7)*c,Rational(5,7)*d].min*2,x].max*1000).to_f