#include <iostream>
#include <iomanip>

using ldouble = long double;

void solve() {
    int k;
    std::cin >> k;

    ldouble ans = 0;
    for (int i = 1; i <= k; ++i) ans += ldouble(1) / i;
    std::cout << std::fixed << std::setprecision(10) << ans / k << "\n";
}

int main() {
    std::cin.tie(nullptr);
    std::ios::sync_with_stdio(false);

    solve();

    return 0;
}