#include<iostream>
#include<cstring>
#include<cstdio>
#include<algorithm>
#include<vector>
#include<set>
#include<map>
#include<queue>
#include<cmath>
#define pi 3.1415927
using namespace std;

int main()
{
    double r;
    while(cin>>r)
    {
        double ans;
        ans = (4.0/3)*pi*r*r*r;
        printf("%.3lf\n",ans);
    }
}