#include <algorithm>
#include <cmath>
#include <iomanip>
#include <iostream>
using namespace std;

struct Point {
  double x, y;
  Point operator+(const Point& p) const { return Point{x+p.x, y+p.y}; }
  Point operator-(const Point& p) const { return Point{x-p.x, y-p.y}; }
  Point operator*(double c) const { return Point{c*x, c*y}; }
  double len() const { return hypot(x, y); }
};

// Positive if b points counterclockwise of a.
inline double CrossProd(const Point& a, const Point& b) {
  return a.x*b.y - a.y*b.x;
}

bool Intersect(const Point& a1, const Point& a2, const Point& b1, const Point& b2) {
  double cp1 = CrossProd(a2-a1, b1-a1);
  double cp2 = CrossProd(a2-a1, b2-a1);
  if (cp1 < -1e-9 && cp2 < -1e-9) return false;
  if (cp1 >  1e-9 && cp2 >  1e-9) return false;
  cp1 = CrossProd(b2-b1, a1-b1);
  cp2 = CrossProd(b2-b1, a2-b1);
  if (cp1 < -1e-9 && cp2 < -1e-9) return false;
  if (cp1 >  1e-9 && cp2 >  1e-9) return false;
  return true;
}

int main() {
  Point a1, a2, b1, b2;
  double ah, bh;
  while (cin >> a1.x >> a1.y >> a2.x >> a2.y >> ah >> b1.x >> b1.y >> b2.x >> b2.y >> bh) {
    double aSideLen = (a2-a1).len();
    double bSideLen = (b2-b1).len();
    double aDiagLen = sqrt(aSideLen*aSideLen/2 + ah*ah);
    double bDiagLen = sqrt(bSideLen*bSideLen/2 + bh*bh);
    double aAltLen = sqrt(aSideLen*aSideLen/4 + ah*ah);
    double bAltLen = sqrt(bSideLen*bSideLen/4 + bh*bh);
    double ret = 1e9;
    for (int ai = 0; ai < 4; ai++) {
      Point ap{a1.y-a2.y, a2.x-a1.x};
      Point amid{(a1+a2)*0.5 + ap*0.5};
      for (int bi = 0; bi < 4; bi++) {
        Point bp{b1.y-b2.y, b2.x-b1.x};
        Point bmid{(b1+b2)*0.5 + bp*0.5};

        for (int aDiag = 0; aDiag < 2; aDiag++) {
          Point at = aDiag ? a1 : (a1+a2)*0.5 + ap*(aAltLen/aSideLen);
          double alen = aDiag ? aDiagLen : 0.0;
          for (int bDiag = 0; bDiag < 2; bDiag++) {
            Point bt = bDiag ? b1 : (b1+b2)*0.5 + bp*(bAltLen/bSideLen);
            double blen = bDiag ? bDiagLen : 0.0;
            if (!aDiag && (CrossProd(bmid-a1, a2-a1) < 0 || !Intersect(a1, a2, at, bt))) continue;
            if (!bDiag && (CrossProd(amid-b1, b2-b1) < 0 || !Intersect(b1, b2, at, bt))) continue;
            ret = min(ret, alen + blen + (bt-at).len());
          }
        }

        b1 = b2+bp; swap(b1, b2);
      }
      a1 = a2+ap; swap(a1, a2);
    }
    cout << fixed << setprecision(9) << ret << endl;
  }
}