#include <bits/stdc++.h>
#define IL inline
#define LL long long
#define eb emplace_back
#define L(i, j, k) for (int i = (j); i <= (k); ++i)
#define R(i, j, k) for (int i = (j); i >= (k); --i)
using namespace std;

using vi = vector<int>;
using db = long double;
constexpr db eps = 1e-12;

struct P {
  db x, y;

#define DEF(o) \
  P& operator o##= (const P &rhs) { x o##= rhs.x, y o##= rhs.y; return *this; } \
  P operator o (const P &rhs) const { return P(*this) o##= rhs; }

  DEF(-) DEF(+)

#undef DEF

#define DEF(o) \
  P& operator o##= (const db &rhs) { x o##= rhs, y o##= rhs; return *this; } \
  P operator o (const db &rhs) const { return P(*this) o##= rhs; }

  DEF(*) DEF(/)

#undef DEF

  db operator * (const P &rhs) const {
    return x * rhs.y - y * rhs.x;
  }

  db norm () {
    return sqrtl(x * x + y * y);
  }

  void chg () {
    swap(x, y);
    x = -x;
  }
} ca[4], cb[4];

IL istream& operator >> (istream &in, P &t) {
  in >> t.x >> t.y;
  return in;
}

struct C {
  P p, q;
  db h;
} a, b;

IL istream& operator >> (istream &in, C &t) {
  in >> t.p >> t.q >> t.h;
  return in;
}

#define D(a, b) (a - b).norm()

IL bool ok (P a, P b, P c, P d) {
  if ((d - b) * (c - d) < 0) {
    return 0;
  }
  return (b - a) * (d - a) >= 0 && (d - a) * (c - a) >= 0;
}

struct V {
  P a, b, c;
  db z;
};

int main () {
  ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
  cin >> a >> b;
  P aa = a.q - a.p;
  ca[0] = a.p;
  L (i, 1, 3) {
    ca[i] = ca[i - 1] + aa;
    aa.chg();
  }
  P bb = b.q - b.p;
  cb[0] = b.p;
  L (i, 1, 3) {
    cb[i] = cb[i - 1] + bb;
    bb.chg();
  }
  db la = sqrtl((aa.x * aa.x + aa.y * aa.y) * 0.25 + a.h * a.h);
  db lb = sqrtl((bb.x * bb.x + bb.y * bb.y) * 0.25 + b.h * b.h);
  db cfa = la / aa.norm();
  db cfb = lb / bb.norm();
  db as = 0x7ffffffff;
  aa.chg();
  bb.chg();
  L (i, 0, 3) {
    aa.chg();
    P ua = ca[i], va = ca[(i + 1) % 4];
    P A = (ua + va) / 2 + aa * cfa;
    vector<V> v0 = {{A, ua, va, 0}, {ua, ua, va, D(A, ua)}, {va, ua, va, D(A, va)}};
    L (j, 0, 3) {
      bb.chg();
      P ub = cb[j], vb = cb[(j + 1) % 4];
      P B = (ub + vb) / 2 + bb * cfb;
      vector<V> v1 = {{B, ub, vb, 0}, {ub, ub, vb, D(B, ub)}, {vb, ub, vb, D(B, vb)}};
      L (_, 0, 2) {
        auto x = v0[_];
        L (__, 0, 2) {
          auto y = v1[__];
          if (_ == 0 && __ == 0) {
            db a1 = abs((y.a - x.b) * (x.b - x.c)) / (x.b - x.c).norm();
            db a2 = abs((x.a - y.b) * (y.b - y.c)) / (y.b - y.c).norm();
            if (a1 + a2 < la + lb) {
              continue;
            }
          }
          if (ok(x.a, x.b, x.c, y.a) && ok(y.a, y.b, y.c, x.a)) {
            as = min(as, D(x.a, y.a) + x.z + y.z);
          }
        }
      }
    }
  }
  cout << fixed << setprecision(9) << as << '\n';
}
// I love WHQ!