#include <iostream>
#include <vector>
using namespace std;

int main() {
    vector<double>H(110, 0);
    H.at(1) = 1;
    for (long long i = 2; i < 110; i++) {
        H.at(i) = H.at(i - 1) + ((double)1 / (double)(i));
    }
    long long k; cin >> k;
    double ans = H.at(k) / (double)k;
    printf("%.12lf", ans);
}