#include <iostream> 
using namespace std;
 
int main(){
    int N;
    cin >> N;
    N--;
    int count = 1;
    while(N != 1){
        if(N == 0){
            cout << 0 << endl;
            return 0;
        }
        N /= 2;
        count++;
    }
    cout << count << endl;
}