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.*;
import java.io.*;

public class AncientBerlandCircus {
    public static InputReader in;
    public static PrintWriter out;

    public static final double EPS = 1e-6;
    public static final int MOD = (int) (1e9 + 7);

    public static void main(String[] args) {
	in = new InputReader(System.in);
	out = new PrintWriter(System.out);
	
	double ax = Double.parseDouble(in.readString());
	double ay = Double.parseDouble(in.readString());
	double bx = Double.parseDouble(in.readString());
	double by = Double.parseDouble(in.readString());
	double cx = Double.parseDouble(in.readString());
	double cy = Double.parseDouble(in.readString());
	
	double qx = 2 * (ax - bx);
	double qy = 2 * (ay - by);
	double qr = ax * ax + ay * ay - bx * bx - by * by;
	
	double rx = 2 * (cx - bx);
	double ry = 2 * (cy - by);
	double rr = cx * cx + cy * cy - bx * bx - by * by;
	
	double det = 1 / (qx * ry - qy * rx);
	double ox = det * (ry * qr - qy * rr);
	double oy = det * (-rx * qr + qx * rr);
	
	double at = StrictMath.atan2(ay - oy, ax - ox);
	double bt = StrictMath.atan2(by - oy, bx - ox);
	double ct = StrictMath.atan2(cy - oy, cx - ox);
	double aaa = at - bt;
	double bbb = bt - ct;
	
	double T = 0.001;
	
	if(aaa < 0)aaa = -aaa;
	if(bbb < 0)bbb = -bbb;
	
	for(int n = 3;n <= 100;n++){
		double theta = 2 * Math.PI / n;
		if(Math.abs(aaa / theta - Math.round(aaa / theta)) < T && Math.abs(bbb / theta - Math.round(bbb / theta)) < T) {
		    double r2 = (ax - ox) * (ax - ox) + (ay - oy) * (ay - oy);
		    out.printf("%1.6f\n", 0.5 * r2 * StrictMath.sin(StrictMath.PI * 2 / n) * n);
		    break;
		}
	}

	out.close();
    }
    


    static class Node implements Comparable<Node> {
	int next;
	int dist;

	public Node(int u, int v) {
	    this.next = u;
	    this.dist = v;
	}

	public void print() {
	    out.println(next + " " + dist + " ");
	}

	public int compareTo(Node that) {
	    return Integer.compare(this.next, that.next);
	}
    }

    static class InputReader {

	private InputStream stream;
	private byte[] buf = new byte[8192];
	private int curChar, snumChars;
	private SpaceCharFilter filter;

	public InputReader(InputStream stream) {
	    this.stream = stream;
	}

	public int snext() {
	    if (snumChars == -1)
		throw new InputMismatchException();
	    if (curChar >= snumChars) {
		curChar = 0;
		try {
		    snumChars = stream.read(buf);
		} catch (IOException e) {
		    throw new InputMismatchException();
		}
		if (snumChars <= 0)
		    return -1;
	    }
	    return buf[curChar++];
	}

	public int nextInt() {
	    int c = snext();
	    while (isSpaceChar(c))
		c = snext();
	    int sgn = 1;
	    if (c == '-') {
		sgn = -1;
		c = snext();
	    }
	    int res = 0;
	    do {
		if (c < '0' || c > '9')
		    throw new InputMismatchException();
		res *= 10;
		res += c - '0';
		c = snext();
	    } while (!isSpaceChar(c));
	    return res * sgn;
	}

	public long nextLong() {
	    int c = snext();
	    while (isSpaceChar(c))
		c = snext();
	    int sgn = 1;
	    if (c == '-') {
		sgn = -1;
		c = snext();
	    }
	    long res = 0;
	    do {
		if (c < '0' || c > '9')
		    throw new InputMismatchException();
		res *= 10;
		res += c - '0';
		c = snext();
	    } while (!isSpaceChar(c));
	    return res * sgn;
	}

	public int[] nextIntArray(int n) {
	    int a[] = new int[n];
	    for (int i = 0; i < n; i++)
		a[i] = nextInt();
	    return a;
	}

	public String readString() {
	    int c = snext();
	    while (isSpaceChar(c))
		c = snext();
	    StringBuilder res = new StringBuilder();
	    do {
		res.appendCodePoint(c);
		c = snext();
	    } while (!isSpaceChar(c));
	    return res.toString();
	}

	public boolean isSpaceChar(int c) {
	    if (filter != null)
		return filter.isSpaceChar(c);
	    return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
	}

	public interface SpaceCharFilter {
	    public boolean isSpaceChar(int ch);
	}
    }
}