#include<iostream>
using namespace std;
double THRESHOLD=0.001;
int coefficients[100];
int n=2;//係數個數-1 
double f(double x){
       double res=0;
       double temp=1;
       for(int i=0;i<n;i++){
           res+=res+coefficients[i]*temp;
           temp*=x;
       }
       return res;
}
double root(double a, double b){
       if(f(a)==0)
          return a;
       if(f(b)==0)
          return b;
       double mid;
       while(b-a>=THRESHOLD){
          mid=(a+b)/2;
          if(f(mid)==0)
             return mid;
          if(f(a)*f(mid)>0)
              a=mid;
          else if(f(b)*f(mid)>0)
              b=mid;                             
       }
       return (a+b)/2;
}
int main()
{
     double a, b;
     for(int i=0; i<n; ++i ) {
         cin>>coefficients[i];
     }
     cin>>a>>b;
     
     printf( "%.2lf", root( a, b ) );
     return 0;
}