include [HTML_REMOVED]

using namespace std;
int main ()
{
double x;
cin>>x;
double l=-10000,r=10000;
while(r-l>1e-8)
{
double mid=(l+r)/2;
if(midmidmid>=x) r=mid;
else l=mid;
}
printf(“%lf\n”,l);
return 0;
}