#include <iostream>
using namespace std;

int binarydigit(int n) {
    int res = 0;
    while (n) {
        res += 1;
        n = n >> 1;
    }
    return res;
}

int main() {
    int N;
    cin >> N;

    int res = binarydigit(N);
    if (!(N & (N - 1))) {
        cout << res - 1 << endl;
    } else {
        cout << res << endl;
    }
}