import java.util.*;
public class Test30{
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		int count = 0;
		
		if(N>0){
			while(N>1){
				N /= 2;
				count++;
			}
			System.out.println(count);
		}
	}
}