import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Arrays;

public class Main {

	public static void main(String[] args) {
	      BufferedReader stdReader =new BufferedReader(new InputStreamReader(System.in));
	      String line = "";
	      int count = -1;
	      try {
	    	  int N = Integer.parseInt(stdReader.readLine());
	    	  while(N >Math.pow(2, (count++ + 1)));
	    	  System.out.println(count);
	    	  } catch (IOException e) {
			e.printStackTrace();
	      }
	}
}