#include<bits/stdc++.h>

#include<bits/stdc++.h>
using namespace std;
double a,b,c,d;
int main()
{
	cin>>a>>b>>c>>d;
	for(double i=-2;i<=100;i+=0.001)
	{
		double j=i+0.001;
		double l=a*i*i*i+b*i*i+c*i+d;
		double r=a*j*j*j+b*j*j+c*j+d;
		if(l*r<=0) 
		{
			cout<<(i+j)/2;
		}
	}
	return 0;
} 

using namespace std;

double a,b,c,d; int main()

{

cin>>a>>b>>c>>d;

for(double i=-2;i<=100;i+=0.001)

{
	double j=i+0.001;
	double l=a*i*i*i+b*i*i+c*i+d;
	double r=a*j*j*j+b*j*j+c*j+d;
	if(l*r<=0) 
	{
		cout<<(i+j)/2;
	}
}
return 0;

}