#include <cstdio>
#include <algorithm>

using namespace std;

#define NrE 3
#define sqr(x) ((x) * (x))
#define INF 1e9

struct Elipsa {
   double cx, cy, rx, ry;
   double a, b, c_part, x0;

   void read() {
      scanf("%lf %lf %lf %lf\n", &cx, &cy, &rx, &ry);
      a = 1.0 / sqr(rx);
      b = -2.0 * cx / sqr(rx);
      c_part = sqr(cx) / sqr(rx) - 1.0;
      x0 = -b / (2.0 * a);
   }

   pair<double, double> intersect(const double y) const {
      if (y < cy - ry || y > cy + ry) {
         return make_pair(0.0, 0.0);
      }
      const double c = c_part + sqr(y - cy) / sqr(ry);
      const double delta = sqr(b) - 4.0 * a * c;
      if (delta < 0) {
         fprintf(stderr, "Error: %lf %lf\n", y, delta);
         //return make_pair(0.0, 0.0);
      }

      const double dif = sqrt(delta) / (2.0 * a);

      return make_pair(cx - dif, cx + dif);
   }
};

Elipsa elipse[NrE];

int main() {
#ifdef WIN32
   freopen("elipse.in", "rb", stdin);
   freopen("elipse.out", "wb", stdout);
#endif
   for (int i = 0; i < NrE; i++) {
      elipse[i].read();
   }

   double ans = 0.0;
   const double PAS = 0.00004;

   for (double y = -76; y <= 76; y += PAS) {
      pair<double, bool> points[2 * NrE];
      for (int i = 0; i < NrE; i++) {
         pair<double, double> interval = elipse[i].intersect(y + PAS * 0.5);
         points[2 * i] = make_pair(interval.first, false);
         points[2 * i + 1] = make_pair(interval.second, true);
      }
      sort(points, points + 2 * NrE);
      double lastPoz = INF;
      double lung = 0.0;
      int nrOpen = 0;

      for (int i = 0; i < 2 * NrE; i++) {
         if (points[i].second) {
            nrOpen--;
            if (nrOpen < 0) {
               fprintf(stderr, "Wrong!\n");
            }
            if (nrOpen == 0) {
               lung += points[i].first - lastPoz;
            }
         } else {
            if (nrOpen == 0) {
               lastPoz = points[i].first;
            }
            nrOpen++;
         }
      }

      const double inc = lung * PAS;
      ans += inc;
   }

   printf("%.8lf", ans);
   return 0;
}