#include <iostream>
#include <iomanip>
#include <cmath>

using ldouble = long double;
constexpr ldouble INF = 1e20;

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

    ldouble ans = 0;
    for (ldouble i = 1; std::pow(i, n) < INF; ++i) {
        ans += std::pow(i, -n);
    }

    std::cout << std::fixed << std::setprecision(10)
              << ans << "\n";
}

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

    solve();

    return 0;
}