poj 2405（水题，pow(n,1/3)开方）

#include<iostream>
#include<cmath>
#include<cstdio>
using namespace std;
#define PI 3.1415927
int main(){
    double D,V,d;
    while(scanf("%lf%lf",&D,&V)==2&&D){
        d = pow((double)D*D*D-V*6/PI,(double)1/3);
        printf("%.3lf\n",d);
    }
    return 0;
}