import java.util.*;

public class Yukicoder_47{
	public static void main(String[] args){
		Scanner stdIn = new Scanner(System.in);
		int N = stdIn.nextInt();
		boolean flag = true;
		if(N==1){
			System.out.println(0);
		}
		else{
			String str = Integer.toBinaryString(N);
			int count = str.length();
			for(int i=1;i<str.length();i++){
				char ch = str.charAt(i);
				if(ch == '1'){
					flag = false;
				}
			}
			if(flag){
				System.out.println(count-1);
			}
			else{
				System.out.println(count);
			}
		}
	}
}