#include <iostream>
#include <iomanip>
#include <cmath>
using namespace std;
int main(){
    int a,b,c,d,e,f;cin>>a>>b>>c>>d>>e>>f;
    double A = a;
    double B = b;
    double aa = -c/(2*A);
    double bb = -d/(2*B);
    double r2 = aa*aa+bb*bb-(e-f);
    cout << fixed << setprecision(10) << sqrt(r2) << endl;
}