using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace algo {
    class Program
    {
        static void Main(string[] args)
        {
            int N = int.Parse(Console.ReadLine()); //.Split(' ');
            int ans = 0;
            if( N == 1)
            {
                N = 0;
            }
            for(int i = 1; i < N; i *= 2)
            {
                ans++;
            }
            Console.WriteLine(ans);
        }
    }
}