#include <iostream>
using namespace std;
int main() {
    int k; cin >> k;
    if(k == 0) {
        cout << "1.6449340668482264" << endl;
        return 0;
    }
    double x = 1;
    for(double c = 2; c <= k; c += 1) {
        x += 1/c;
    }
    x /= k;
    cout << x << endl;
}