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

namespace yukicoder
{
    class yc
    {
        static void Main()
        {
            int N = int.Parse(Console.ReadLine());
            int cout = 0;

            for (int i = 1; i < N;i *= 2)
            {
                cout++;
            }
            Console.WriteLine(cout);
        }
    }
}