include[HTML_REMOVED]

using namespace std;

int main ()
{
double x;
cin >> x;
double l = -10000,r = 10000;
//因为要保留6位小数
while(r - l> 1e-8){
double mid = (l+r)/2;
if(midmidmid >= x) r =mid;
else l = mid;
}
printf(“%lf\n”,l);
return 0;

}