#include <bits/stdc++.h>   using namespace std;   double cooy1, cooy2, cooyw, cooxb, cooyb, r;   double s1, s2;   int main() {     ios_base::sync_with_stdio(false);     cin >> cooy1 >> cooy2 >> cooyw >> cooxb >> cooyb >> r;     cooy1 += r;     cooy2 -= r;     cooyw -= r;     s1 = 2 * cooyw - cooy1;     s2 = 2 * cooyw - cooy2;     double xx1 = cooxb * (cooyw - s1) / (cooyb - s1);     double xx2 = cooxb * (cooyw - s2) / (cooyb - s2);     double dd1 = sqrt(cooxb * cooxb + (s1 - cooyb) * (s1 - cooyb)) * r / cooxb;     double dd2 = sqrt(cooxb * cooxb + (s2 - cooyb) * (s2 - cooyb)) * r / cooxb;     if (s1 - dd1 < s2 - r) {       if (s2 - dd2 < s2 - r) {         cout << -1;         return 0;       }       cout.precision(30);       cout << xx2;       return 0;     } else {       cout.precision(30);       cout << xx1;     }   }   