Problem: Nowadays all circuses in Berland have a round arena with diameter 13 meters, but in the past things were different.

In Ancient Berland arenas in circuses were shaped as a regular (equiangular) polygon, the size and the number of angles could vary from one circus to another. In each corner of the arena there was a special pillar, and the rope strung between the pillars marked the arena edges.

Recently the scientists from Berland have discovered the remains of the ancient circus arena. They found only three pillars, the others were destroyed by the time.

You are given the coordinates of these three pillars. Find out what is the smallest area that the arena could have.

Input

The input file consists of three lines, each of them contains a pair of numbers –– coordinates of the pillar. Any coordinate doesn't exceed 1000 by absolute value, and is given with at most six digits after decimal point.

Output

Output the smallest possible area of the ancient arena. This number should be accurate to at least 6 digits after the decimal point. It's guaranteed that the number of angles in the optimal polygon is not larger than 100.

Examples

Input

0.000000 0.000000
1.000000 1.000000
0.000000 1.000000


Output

1.00000000

Solution (in CPP):

Solution:
#include <bits/stdc++.h>
using namespace std;
long double PI = 3.14159265359;
long double eps = 1e-5;
long double getArea(long double x1, long double y1, long double x2,
                    long double y2, long double x3, long double y3) {
  long double ret = 0.0;
  ret += x1 * (y2 - y3) + x2 * (y3 - y1) + x3 * (y1 - y2);
  ret = fabs(ret);
  ret /= 2.0;
  return ret;
}
long double getDist(long double x1, long double y1, long double x2,
                    long double y2) {
  long double ret = (x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2);
  return sqrt(ret);
}
bool EQ(long double a, long double b) {
  if (fabs(a - b) < eps) return true;
  return false;
}
int main() {
  long double x1, y1, x2, y2, x3, y3;
  cin >> x1 >> y1 >> x2 >> y2 >> x3 >> y3;
  long double dis1 = 1.0 * getDist(x1, y1, x2, y2);
  long double dis2 = 1.0 * getDist(x3, y3, x2, y2);
  long double dis3 = 1.0 * getDist(x1, y1, x3, y3);
  long double area = 1.0 * getArea(x1, y1, x2, y2, x3, y3);
  long double rad = 1.0 * dis1 * dis2 * dis3 / 4.0;
  rad /= 1.0 * area;
  long double ang1 = 1.0 * acos(1.0 - (dis1 * dis1) / (2.0 * rad * rad));
  long double ang2 = 1.0 * acos(1.0 - (dis2 * dis2) / (2.0 * rad * rad));
  long double ang3 = 1.0 * acos(1.0 - (dis3 * dis3) / (2.0 * rad * rad));
  for (int i = 3; i <= 100; i++) {
    bool f = true;
    long double ang = 2.0 * PI / i;
    long double temp1 = 1.0 * ang1 / ang;
    long double temp2 = 1.0 * ang2 / ang;
    long double temp3 = 1.0 * ang3 / ang;
    int fl = floor(1.0 * temp1);
    int cl = ceil(1.0 * temp1);
    if (!(EQ(1.0 * temp1, 1.0 * fl) or EQ(1.0 * temp1, 1.0 * cl))) f = false;
    fl = floor(1.0 * temp2);
    cl = ceil(1.0 * temp2);
    if (!(EQ(1.0 * temp2, 1.0 * fl) or EQ(1.0 * temp2, 1.0 * cl))) f = false;
    fl = floor(1.0 * temp3);
    cl = ceil(1.0 * temp3);
    if (!(EQ(1.0 * temp3, 1.0 * fl) or EQ(1.0 * temp3, 1.0 * cl))) f = false;
    if (f) {
      long double ans = i;
      ans /= 2.0;
      ans *= 1.0 * rad * rad;
      ans *= 1.0 * sin(2.0 * PI / i);
      cout << fixed << setprecision(6) << ans << endl;
      return 0;
    }
  }
  return 0;
}