pow求解
#include<cstdio>
#include<iostream>
#include<cstring>
#include<cmath>
#include<algorithm>
using namespace std;
int main()
{
double n;
scanf("%lf",&n);
if(n>=0)
{
printf("%lf\n",pow(n,(double)1.0/3));
}
else
{
printf("%lf\n",-pow(-n,(double)1.0/3));
}
return 0;
}