/* 
2002 計(jì)算球體積 
Time Limit : 1000 ms  Memory Limit : 32768 K  Output Limit : 256 K 

GUN C 
*/ 

#include <stdio.h> 

#define PI 3.1415927 

int main() 
{ 
    double v,r; 
    while(scanf("%lf",&r)==1) 
    { 
        v=r*r*r*PI*4/3; 
        printf("%.3lf\n",v); 
    } 
    return 0; 
}