#include <bits/stdc++.h>
using namespace std;
int main() {
    long long a;
    int i = 1;
    cin >> a;
    while (a > 1) {
        a = (long long)floor(a / 2);
        i++;
    }
    if (i == 1)
        i = 0;
    cout << i;
    return 0;
}