#include <iostream>
#include <bits/stdc++.h>
using namespace std;

int main() {
	int n = 0;
	double sum = 0;
    cin>>n;

	for (int i = 1; i <= n; i++) {
		sum += 1.0 / i;
	}
	cout << fixed << setprecision(6) << sum;

	system("pause");
	return 0;
 }