#include <iostream>
#include <vector>
using namespace std;
int solve (int n) {
    vector < int > a (n + 1);
    a[1] = 0;
    a[2] = 1;

    for (int i = 3, step = 0; i <= n; i += step) {
        step = a[i - 1] + 1;
        for (int j = i; j <= n && j <= (i + step - 1); j++) {
            a[j] = step;
        }
    }

    return a[n];
}
int main() {
    int n;
    cin >> n;

    cout << solve(n) << endl;
    return 0;
}