#include <iostream>
#include <vector>

using namespace std;

struct Point {
  double x, y;
  Point(double x, double y) : x(x), y(y) {}
  Point &operator+=(Point p) {
    x += p.x;
    y += p.y;
    return *this;
  }
  Point &operator-=(Point p) {
    x -= p.x;
    y -= p.y;
    return *this;
  }
  Point operator+(Point p) { return Point(*this) += p; }
};

double Area(Point a, Point b, Point c) {
  a -= c;
  b -= c;
  return abs((a.x * b.y - a.y * b.x) / 2.0);
}

int main() {
  int x1, y1, x2, y2, x3, y3;
  cin >> x1 >> y1 >> x2 >> y2 >> x3 >> y3;
  Point p1(x1, y1), p2(x2, y2), p3(x3, y3);

  vector<Point> dp;
  dp.emplace_back(1, 0);
  dp.emplace_back(-1, 0);
  dp.emplace_back(0, 1);
  dp.emplace_back(0, -1);

  double res = 0.0;
  for (auto d1 : dp) {
    for (auto d2 : dp) {
      for (auto d3 : dp) {
        auto pp1 = p1 + d1;
        auto pp2 = p2 + d2;
        auto pp3 = p3 + d3;
        res = max(res, Area(pp1, pp2, pp3));
      }
    }
  }

  cout << res << endl;
  return 0;
}