t = gets.to_i
n = gets.to_i
c_list = gets.split.map(&:to_i)
v_list = gets.split.map(&:to_i)

a_list = c_list + v_list
list = [[t, 0, a_list]]
max_manzoku = 0
loop do
  next_list = []
  list.each do |ima|
    (0...n).each do |i|
      nokori = ima[0] - ima[2][i]
      next_manzoku = ima[1] + ima[2][i + n]
      if nokori < 0
        next
      end
      if max_manzoku < next_manzoku
        max_manzoku = next_manzoku
      end
      if nokori > 0
        next_at = ima[2].dup
        next_at[i + n] /= 2
        next_list << [nokori, next_manzoku, next_at]
      end
    end
  end
  if next_list.empty?
    break
  end
  list = next_list
end
puts max_manzoku