#include<bits/stdc++.h> using namespace std; int main() { double a , b , c , d; cin >> a >> b >> c >> d; for(double i=-100;i<=100;i+=0.001)if(fabs(i*i*i*a+i*i*b+i*c+d)<0.0001)printf("%.02lf",i); return 0; }