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 JAVA):

Solution:
import java.util.Scanner;

//http://codeforces.com/contest/1/problem/C

// Could not figure this out initially. I used the help from : http://codeforces.com/blog/entry/495 to solve it.

public class MainC {
	@SuppressWarnings("resource")
	public static void main(String[] args) {
		Scanner in = new Scanner(System.in);

		double ax = in.nextDouble(), ay = in.nextDouble(); // first coordinate
		double bx = in.nextDouble(), by = in.nextDouble(); // second coordinate
		double cx = in.nextDouble(), cy = in.nextDouble(); // third coordinate

		double lenAB = getLength(ax, bx, ay, by); // length of triangle sides
		double lenAC = getLength(ax, cx, ay, cy);
		double lenBC = getLength(bx, cx, by, cy);

		double triArea = getArea(lenAB, lenAC, lenBC); // area of this triangle
		double radius = (lenAB * lenAC * lenBC) / (4 * triArea); // the radius of the circle that encompasses this triangle

		double angleA = Math.acos((Math.pow(lenAC, 2) + Math.pow(lenBC, 2) - Math.pow(lenAB, 2)) / (2 * lenAC * lenBC)); // triangle interior angles
		double angleB = Math.acos((Math.pow(lenAB, 2) + Math.pow(lenBC, 2) - Math.pow(lenAC, 2)) / (2 * lenAB * lenBC));
		double angleC = Math.acos((Math.pow(lenAB, 2) + Math.pow(lenAC, 2) - Math.pow(lenBC, 2)) / (2 * lenAB * lenAC));

		double n = Math.PI / getGDC(getGDC(angleA, angleB), angleC); // The number of sides for this polygon.
		double area = (Math.pow(radius, 2) * n * Math.sin((2 * Math.PI) / n)) / 2; // the area as a sum of triangles.

		System.out.println(String.format("%.8f", area));
	}

	public static final double getLength(double ax, double bx, double ay, double by) {
		double difX = ax - bx;
		double difY = ay - by;

		return Math.sqrt(Math.pow(difX, 2) + Math.pow(difY, 2));
	}

	public static final double getGDC(double x, double y) {
		while (Math.abs(x) > 0.0001 && Math.abs(y) > 0.0001) {
			if (x > y) {
				x -= Math.floor(x / y) * y;
			} else {
				y -= Math.floor(y / x) * x;
			}
		}
		return x + y;
	}

	public static final double getArea(double a, double b, double c) {
		double s = (a + b + c) / 2;
		return Math.sqrt(s * (s - a) * (s - b) * (s - c));
	}
}