def solution(n)
  gap = 0
  maxgap = 0
  bin = []
  
  # revert number
  while n > 0 do
    bin.unshift(n%2)
    n = (n>>1)
  end
    
  # count
  bin.each do |b|
    if b != 0 then
      maxgap = gap if gap > maxgap
      gap = 0
      next
    end
    gap += 1
  end
  return maxgap
end