#include
#include
double a=1.0,b=1.5,c;
double result(double t)
{
return pow(t,3)-t-1;
}
int main()
{
do
{
c=(a+b)/2;
if (result(c)<0) a=c;
else if (result(c)>0) b=c;
}
while( result (c)!=0|| b-a>1e-5) ;
printf("%.5lf",result(c));
return 0;
}