defmodule Main do
  def main do
    n = IO.gets("") |> String.trim |> String.to_integer
    strike(1, n, 0)
  end
  
  def strike(biscuit, n, count) when biscuit < n do
    strike(pocket(biscuit), n, count + 1)
  end
  
  def strike(_biscuit, _n, count) do
   IO.puts count
  end
  
  def pocket(n) do
    n * 2
  end
end