# frozen_string_literal: true

n, k = gets.chomp.split.map(&:to_i)

n2 = 50.0 * n
k2 = Rational('0.8') + Rational('0.2') * k
f = n2 / k2
# p "n2: #{n2}, k2: #{k2}, f: #{f}"

p 50 * n + f.floor