#include<iostream> #include<cstdio> using namespace std; int main() { /* double a,b,c; scanf("%lf%lf",&a,&b); printf("%.2lf",a/b); */ double n=3.1415926; double b,c; scanf("%lf",&b); c=4/3*n*b*b*b; printf("%.4lf",c); return 0; }