#include<iostream>
#include<cmath>
using namespace std;

int main(){
    int n, i = 0;
    cin >> n;

    int count = 0, j = 1;
    for(i = 0; i < 10000000; i++){
        if(j * 2 < n){
            j = pow(2, count);
            count++;
        }
        else if(j * 2 >= n)break;
    }
    cout << i << endl;
}