include[HTML_REMOVED]

using namespace std;
int main(){
double n;
cin>>n;
double l=-10000;
double r=10000;
while(r-l>1e-7)
{
double mid=(l+r)/2;
if(midmidmid>=n) r=mid;
if(midmidmid<n) l=mid;
}
printf(“%.6lf”,l);
return 0;
}