import java.util.Scanner;
public class CopyOfMain {
	public static void main(String[] args){
		Scanner S = new Scanner(System.in);
		int N = S.nextInt();
		
		if(N==1)
			System.out.println(0);
		
		String n = Integer.toBinaryString(N+1);
		int tmp = n.length()-1;
		
		System.out.println(tmp);
	}
}