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

using ldouble = long double;

std::vector<ldouble> coef{0, -6, 15, -20, 15, -6, 1};

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

    ldouble ans = 0;
    for (int k = 1; k <= 6; ++k) {
        ans += coef[k] * std::pow(ldouble(k) / 6, 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;
}