import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		long n = sc.nextLong();
		sc.close();

		int eat = 1;
		int count = 0;
		while(eat < n){
			count++;
			if(eat*2 > n) {
				break;
			}
			eat = eat * 2;
		}
		System.out.println(count);
	}
}