include[HTML_REMOVED]
include[HTML_REMOVED]
using namespace std;
double n,l,r,mid;
bool flag;
double q(double a){
return aaa;
}
int main(){
cin>>n;
l=-10000,r=10000;
while(r-l>=1e-7){
mid=(l+r)/2;
if(q(mid)>=n) r=mid;
else l=mid;
}
cout<<fixed<<setprecision(6)<<l;
return 0;
}