#include<stdio.h>
#define t 3.1415926
int main()
{
double a,b;
scanf("%lf",&a);
b = t*4/3*a*a*a;
printf("%.3lf",b);
return 0;
}
#define t 3.1415926
int main()
{
double a,b;
scanf("%lf",&a);
b = t*4/3*a*a*a;
printf("%.3lf",b);
return 0;
}