#define _USE_MATH_DEFINES
#include <iostream>
#include <cmath>

using namespace std;
int main()
{
    double ans;
    double a;
    double cons;
    int ans2;
    cin >> a;

    cons = (pow(M_PI, 2.0))/6;
    ans = (1/a)*pow(cons, a);
    ans2=ans;
    cout << ans2 << endl;
}