//=================================
// Created on: 2018/09/19 15:36:13
//=================================
#include <bits/stdc++.h>
using ld = long double;
constexpr ld PI = 3.14159265359;
int main()
{
    ld a, b;
    std::cin >> a >> b;
    std::cout << std::fixed << std::setprecision(15) << b * b * b * 4 / 3 * PI << std::endl;
    return 0;
}

