N=gets.chomp.to_i

def nishinsuu(num)
  org_num = num
  keta = 1
  total = 0
  while num > 0
    num = num >> 1
    keta += 1
  end
  saidaiketa = keta - 1
  amari =0
  if org_num % (2 ** (saidaiketa-1)) != 0
    amari = 1
  end
  return (saidaiketa - 1) + amari
end

puts nishinsuu(N)