import java.io.*;
class no47
{
    public static void main(String args[])throws IOException
    {
	BufferedReader sc=new BufferedReader(new InputStreamReader(System.in));
	int ans=0;
	int n=Integer.parseInt(sc.readLine());
	for(int idx=1;idx<n;idx*=2)ans++;
	System.out.println(ans);
    }
}