using System;
using System.Text;
using System.Collections.Generic;
using System.Linq;

class Program
{
    static void Main()
    {
        int n = int.Parse(Console.ReadLine());
        string s = Convert.ToString(n, 2);
        if(s.ToCharArray().Count(c => c == '1') == 1)
        {
            Console.WriteLine($"{s.Length - 1}");
        }
        else
        {
            Console.WriteLine($"{s.Length}");
        }
    }
}