杭电OJ2002

#include <iostream>
#include <iomanip>
using namespace std;
#define PI 3.1415927
int main()
{
	double r, v;
	while (cin >> r)
	{
		v = PI*r*r*r*(4.0 / 3);
		cout << setprecision(3) << fixed << v << endl;
	}
}