HDU-2002

#include<iostream>
#define PI 3.1415927
using namespace std;
int main(){
	double a,res;
	while(cin>>a){
		res=PI*a*a*a*4/3;
		cout.setf(ios::fixed);
		cout.precision(3);
		cout<<res<<endl;
	}
	return 0;
}