#include <iostream>
#include <fstream>
#include <vector>
#include <string>
#include <algorithm>
#include <cmath>
//---------------------------
using namespace std;
//---------------------------
#define REP(i,n) for(int i = 0; i < (n); i++)
#define P(x) cout << (x) << "\n"
//---------------------------

int main(){
  std::ios::sync_with_stdio(false);
  std::cin.tie(0);


  int n;cin >> n;
  int t = 0;
  int m = 0;
  while (1) {
    int a;
    a = n - pow(2,m);
    if (a < 0) {
      t = m;
      break;
    }else{
      m++;
    }
  }
  cout << (n - pow(2,t-1) == 0 ? t-1 : t);
  return 0;
}