#include<iostream>
#include<algorithm>
#include<stdio.h>
#include<stdlib.h>
#include<vector>
#include<string>
#include<sstream>
using namespace std;


int main(){

  int n;
  int ans;
  cin >> n;
  for(int i=1;i<n;i=i*2){
    // cout<< i << endl;
    ans++;
  }
  cout << ans << endl;
  return 0;
}