#include <iostream>
#include <cmath>

using ldouble = long double;
const ldouble PI = std::acos(-1.L);

void solve() {
    int n;
    std::cin >> n;
    std::cout << std::lround(std::floor(std::pow((PI * PI) / 6, n) / n)) << "\n";
}

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

    solve();

    return 0;
}