#include<bits/stdc++.h>
using namespace std;
typedef pair<int, int> pii;

int n, ans;


int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    
    cin >> n;
    if (n == 1) {
        cout << 0 << endl;
        return 0;
    }
    if (n % 2 != 0) {
        n += 1;
        cout << n/2 + 1 << endl;
        
    } else {
        cout << (int)(log2(n)) << endl;
            
    }
    

}