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

using ldouble = long double;

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

    ldouble ans = 0;
    for (int n = 20; n >= 1; --n) {
        ans += std::sin(n * k) / std::pow(ldouble(n), n);
    }

    std::cout << ans << "\n";
}

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

    std::cout << std::fixed << std::setprecision(10);

    solve();

    return 0;
}