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.io.*;
import java.util.*;
import java.math.*;

public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        OutputWriter out = new OutputWriter(outputStream);
        Task solver = new C();
        solver.solve(1, in, out);
        out.close();
    }
}

interface Task {
    public void solve(int testNumber, InputReader in, OutputWriter out);
}

class A implements Task {
    public void solve(int testNumber, InputReader in, OutputWriter out){
        
    }
}

class B implements Task {
    public void solve(int testNumber, InputReader in, OutputWriter out) {
        int n=in.readInt();
        String str;
        StringBuilder s1, s2;
        boolean primeiro;
        while (n-->0) {
            str=in.next();
            primeiro=true;
            s1=new StringBuilder();
            s2=new StringBuilder();
            for (int i=1; i<str.length(); i++) 
                if (isDigit(str.charAt(i-1)) && !isDigit(str.charAt(i))) primeiro=false;
            //out.printLine(str+" "+primeiro);
            if (primeiro) {
                for (int i=0; i<str.length(); i++) {
                    if (isDigit(str.charAt(i))) s1.append(str.charAt(i));
                    else s2.append(str.charAt(i));
                }
                str=new String("R"+s1+"C"+f1(s2));
            }
            else {
                boolean flagC=false;
                for (int i=0; i<str.length(); i++) {
                    if (str.charAt(i)=='C') flagC=true;
                    else if (isDigit(str.charAt(i))) {
                        if (flagC) s2.append(str.charAt(i));
                        else s1.append(str.charAt(i));
                    }
                }
                str=new String(f2(Integer.parseInt(s2.toString()))+s1);
            }
            out.printLine(str);
        }
    }
    
    boolean isDigit(char c) {
        return c>='0' && c<='9';
    }
    
    int f1(StringBuilder str) {
        int ret=0;
        for (int i=0; i<str.length(); i++) ret=26*ret+str.charAt(i)-'A'+1;
        return ret;
    }
    
    String f2(int n) {
        StringBuilder ret=new StringBuilder();
        for (; n>0; n/=26) {
            n--;
            ret.insert(0, (char)('A'+n%26));
            //System.out.println(n+" "+('A'+n%26));
        }
        return ret.toString();
    }
    
}

class C implements Task {
    public void solve(int testNumber, InputReader in, OutputWriter out){
        Point p0=new Point(in.readDouble(), in.readDouble()), 
                p1=new Point(in.readDouble(), in.readDouble()), 
                p2=new Point(in.readDouble(), in.readDouble());
        Vector v01=new Vector(p0, p1), v02=new Vector(p0, p2), v12=new Vector(p1, p2);
        double R=0.5*v01.length()*v02.length()*v12.length()/cross(v01, v02);
        Angle A=new Angle(p0, p1, p2), B=new Angle(p1, p2, p0), C=new Angle(p2, p0, p1);
        int n=(int) (2.0*Math.PI/gcd(gcd(A.value(), B.value()), C.value()));
        out.print(0.5*n*R*R*Math.sin(2.0*Math.PI/n)*Math.cos(2.0*Math.PI/n));
    }
    
    double cross(Vector v0, Vector v1) {
        return Math.abs(v0.x*v1.y-v0.y*v1.x);
    }
    
    double gcd(double a, double b) {
        if (Math.abs(b)<GeometryUtils.epsilon) return a;
        return gcd(b, a%b);
    }
    
}

class Vector {
    public final double x;
    public final double y;
    public final Point point;

    public Vector(double x, double y) {
            this.x = x;
            this.y = y;
            point = new Point(x, y);
    }

    public Vector(Point point) {
            this.x = point.x;
            this.y = point.y;
            this.point = point;
    }

    public Vector(Point from, Point to) {
            this(to.x - from.x, to.y - from.y);
    }

    public double angleTo(Vector other) {
            return GeometryUtils.canonicalAngle(other.point.angle() - point.angle());
    }

    public double length() {
            return point.value();
    }

    public double angle() {
            return point.angle();
    }
}

class Point {
    public static final Point ORIGIN = new Point(0, 0);
    public final double x;
    public final double y;

    @Override
    public String toString() {
        return "(" + x + ", " + y + ")";
    }

    public Point(double x, double y) {
        this.x = x;
        this.y = y;
    }

    public Line line(Point other) {
        if (equals(other))
            return null;
        double a = other.y - y;
        double b = x - other.x;
        double c = -a * x - b * y;
        return new Line(a, b, c);
    }

    @Override
    public boolean equals(Object o) {
        if (this == o)
            return true;
        if (o == null || getClass() != o.getClass())
            return false;

        Point point = (Point) o;

        return Math.abs(x - point.x) <= GeometryUtils.epsilon && Math.abs(y - point.y) <= GeometryUtils.epsilon;
    }

    @Override
    public int hashCode() {
        int result;
        long temp;
        temp = x != +0.0d ? Double.doubleToLongBits(x) : 0L;
        result = (int) (temp ^ (temp >>> 32));
        temp = y != +0.0d ? Double.doubleToLongBits(y) : 0L;
        result = 31 * result + (int) (temp ^ (temp >>> 32));
        return result;
    }

    public double distance(Point other) {
        return GeometryUtils.fastHypot(x - other.x, y - other.y);
    }

    public double distance(Line line) {
        return Math.abs(line.a * x + line.b * y + line.c);
    }

    public double value() {
        return GeometryUtils.fastHypot(x, y);
    }

    public double angle() {
        return Math.atan2(y, x);
    }

    public static Point readPoint(InputReader in) {
        double x = in.readDouble();
        double y = in.readDouble();
        return new Point(x, y);
    }

    public Point rotate(double angle) {
        double nx = x * Math.cos(angle) - y * Math.sin(angle);
        double ny = y * Math.cos(angle) + x * Math.sin(angle);
        return new Point(nx, ny);
    }
}

class Angle {
    public final Point o;
    public final Point a;
    public final Point b;

    public Angle(Point o, Point a, Point b) {
        this.o = o;
        this.a = a;
        this.b = b;
    }

    public double value() {
        double ab = a.distance(b);
        double ao = a.distance(o);
        double bo = b.distance(o);
        return Math.acos((ao * ao + bo * bo - ab * ab) / (2 * ao * bo));
    }

}

class GeometryUtils {
    public static double epsilon = 1e-4;

    public static double fastHypot(double...x) {
        if (x.length == 0)
            return 0;
        else if (x.length == 1)
            return Math.abs(x[0]);
        else {
            double sumSquares = 0;
            for (double value : x)
                sumSquares += value * value;
            return Math.sqrt(sumSquares);
        }
    }

    public static double fastHypot(double x, double y) {
        return Math.sqrt(x * x + y * y);
    }

    public static double fastHypot(double[] x, double[] y) {
        if (x.length == 0)
            return 0;
        else if (x.length == 1)
            return Math.abs(x[0]- y[0]);
        else {
            double sumSquares = 0;
            for (int i = 0; i < x.length; i++) {
                double diff = x[i] - y[i];
                sumSquares += diff * diff;
            }
            return Math.sqrt(sumSquares);
        }
    }

    public static double fastHypot(int[] x, int[] y) {
        if (x.length == 0)
            return 0;
        else if (x.length == 1)
            return Math.abs(x[0]- y[0]);
        else {
            double sumSquares = 0;
            for (int i = 0; i < x.length; i++) {
                double diff = x[i] - y[i];
                sumSquares += diff * diff;
            }
            return Math.sqrt(sumSquares);
        }
    }

    public static double missileTrajectoryLength(double v, double angle, double g) {
        return (v * v * Math.sin(2 * angle)) / g;
    }

    public static double sphereVolume(double radius) {
        return 4 * Math.PI * radius * radius * radius / 3;
    }

    public static double triangleSquare(double first, double second, double third) {
        double p = (first + second + third) / 2;
        return Math.sqrt(p * (p - first) * (p - second) * (p - third));
    }

    public static double canonicalAngle(double angle) {
        while (angle > Math.PI)
            angle -= 2 * Math.PI;
        while (angle < -Math.PI)
            angle += 2 * Math.PI;
        return angle;
    }

    public static double positiveAngle(double angle) {
        while (angle > 2 * Math.PI - GeometryUtils.epsilon)
            angle -= 2 * Math.PI;
        while (angle < -GeometryUtils.epsilon)
            angle += 2 * Math.PI;
        return angle;
    }
}

class Line {
    public final double a;
    public final double b;
    public final double c;

    public Line(Point p, double angle) {
        a = Math.sin(angle);
        b = -Math.cos(angle);
        c = -p.x * a - p.y * b;
    }

    public Line(double a, double b, double c) {
        double h = GeometryUtils.fastHypot(a, b);
        this.a = a / h;
        this.b = b / h;
        this.c = c / h;
    }

    public Point intersect(Line other) {
        if (parallel(other))
            return null;
        double determinant = b * other.a - a * other.b;
        double x = (c * other.b - b * other.c) / determinant;
        double y = (a * other.c - c * other.a) / determinant;
        return new Point(x, y);
    }

    public boolean parallel(Line other) {
        return Math.abs(a * other.b - b * other.a) < GeometryUtils.epsilon;
    }

    public boolean contains(Point point) {
        return Math.abs(value(point)) < GeometryUtils.epsilon;
    }

    public Line perpendicular(Point point) {
        return new Line(-b, a, b * point.x - a * point.y);
    }

    public double value(Point point) {
        return a * point.x + b * point.y + c;
    }

    public Point[] intersect(Circle circle) {
        double distance = distance(circle.center);
        if (distance > circle.radius + GeometryUtils.epsilon)
            return new Point[0];
        Point intersection = intersect(perpendicular(circle.center));
        if (Math.abs(distance - circle.radius) < GeometryUtils.epsilon)
            return new Point[]{intersection};
        double shift = Math.sqrt(circle.radius * circle.radius - distance * distance);
        return new Point[]{new Point(intersection.x + shift * b, intersection.y - shift * a),
            new Point(intersection.x - shift * b, intersection.y + shift * a)};
    }

    public double distance(Point center) {
        return Math.abs(value(center));
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;

        Line line = (Line) o;

        if (!parallel(line)) return false;
        if (Math.abs(a * line.c - c * line.a) > GeometryUtils.epsilon || Math.abs(b * line.c - c * line.b) > GeometryUtils.epsilon) return false;

        return true;
    }
}

class Circle {
    public final Point center;
    public final double radius;

    public Circle(Point center, double radius) {
        this.center = center;
        this.radius = radius;
    }

    public boolean contains(Point point) {
        return center.distance(point) < radius + GeometryUtils.epsilon;
    }

    public boolean strictContains(Point point) {
        return center.distance(point) < radius - GeometryUtils.epsilon;
    }

    public Point[] findTouchingPoints(Point point) {
        double distance = center.distance(point);
        if (distance < radius - GeometryUtils.epsilon)
            return new Point[0];
        if (distance < radius + GeometryUtils.epsilon)
            return new Point[]{point};
        Circle power = new Circle(point, Math.sqrt((distance - radius) * (distance + radius)));
        return intersect(power);
    }

    public Point[] intersect(Circle other) {
        double distance = center.distance(other.center);
        if (distance > radius + other.radius + GeometryUtils.epsilon || Math.abs(radius - other.radius) > distance + GeometryUtils.epsilon)
            return new Point[0];
        double p = (radius + other.radius + distance) / 2;
        double height = 2 * Math.sqrt(p * (p - radius) * (p - other.radius) * (p - distance)) / distance;
        double l1 = Math.sqrt(radius * radius - height * height);
        double l2 = Math.sqrt(other.radius * other.radius - height * height);
        if (radius * radius + distance * distance < other.radius * other.radius)
            l1 = -l1;
        if (radius * radius > distance * distance + other.radius * other.radius)
            l2 = -l2;
        Point middle = new Point((center.x * l2 + other.center.x * l1) / (l1 + l2),
            (center.y * l2 + other.center.y * l1) / (l1 + l2));
        Line line = center.line(other.center).perpendicular(middle);
        return line.intersect(this);
    }
}

class D implements Task {
    public void solve(int testNumber, InputReader in, OutputWriter out){
        
    }
}

class E implements Task {
    public void solve(int testNumber, InputReader in, OutputWriter out){
        
    }
}

class InputReader {

    private InputStream stream;
    private byte[] buf = new byte[1024];
    private int curChar;
    private int numChars;
    private SpaceCharFilter filter;

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

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

    public int peek() {
        if (numChars == -1)
            return -1;
        if (curChar >= numChars) {
            curChar = 0;
            try {
                numChars = stream.read(buf);
            } catch (IOException e) {
                return -1;
            }
            if (numChars <= 0)
                return -1;
        }
        return buf[curChar];
    }

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

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

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

    public boolean isSpaceChar(int c) {
        if (filter != null)
            return filter.isSpaceChar(c);
        return isWhitespace(c);
    }

    public static boolean isWhitespace(int c) {
        return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
    }

    private String readLine0() {
        StringBuilder buf = new StringBuilder();
        int c = read();
        while (c != '\n' && c != -1) {
            if (c != '\r')
                buf.appendCodePoint(c);
            c = read();
        }
        return buf.toString();
    }

    public String readLine() {
        String s = readLine0();
        while (s.trim().length() == 0)
            s = readLine0();
        return s;
    }

    public String readLine(boolean ignoreEmptyLines) {
        if (ignoreEmptyLines)
            return readLine();
        else
            return readLine0();
    }

    public BigInteger readBigInteger() {
        try {
            return new BigInteger(readString());
        } catch (NumberFormatException e) {
            throw new InputMismatchException();
        }
    }

    public char readCharacter() {
        int c = read();
        while (isSpaceChar(c))
            c = read();
        return (char) c;
    }

    public double readDouble() {
        int c = read();
        while (isSpaceChar(c))
            c = read();
        int sgn = 1;
        if (c == '-') {
            sgn = -1;
            c = read();
        }
        double res = 0;
        while (!isSpaceChar(c) && c != '.') {
            if (c == 'e' || c == 'E')
                return res * Math.pow(10, readInt());
            if (c < '0' || c > '9')
                throw new InputMismatchException();
            res *= 10;
            res += c - '0';
            c = read();
        }
        if (c == '.') {
            c = read();
            double m = 1;
            while (!isSpaceChar(c)) {
                if (c == 'e' || c == 'E')
                    return res * Math.pow(10, readInt());
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                m /= 10;
                res += (c - '0') * m;
                c = read();
            }
        }
        return res * sgn;
    }

    public boolean isExhausted() {
        int value;
        while (isSpaceChar(value = peek()) && value != -1)
            read();
        return value == -1;
    }

    public String next() {
        return readString();
    }

    public SpaceCharFilter getFilter() {
        return filter;
    }

    public void setFilter(SpaceCharFilter filter) {
        this.filter = filter;
    }

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

class OutputWriter {
    private final PrintWriter writer;

    public OutputWriter(OutputStream outputStream) {
        writer = new PrintWriter(new BufferedWriter(new OutputStreamWriter(outputStream)));
    }

    public OutputWriter(Writer writer) {
        this.writer = new PrintWriter(writer);
    }

    public void print(char[] array) {
        writer.print(array);
    }

    public void print(Object...objects) {
        for (int i = 0; i < objects.length; i++) {
            if (i != 0)
                writer.print(' ');
            writer.print(objects[i]);
        }
    }

    public void print(int[] array) {
        for (int i = 0; i < array.length; i++) {
            if (i != 0)
                writer.print(' ');
            writer.print(array[i]);
        }
    }

    public void print(long[] array) {
        for (int i = 0; i < array.length; i++) {
            if (i != 0)
                writer.print(' ');
            writer.print(array[i]);
        }
    }

    public void printLine(int[] array) {
        print(array);
        writer.println();
    }

    public void printLine(long[] array) {
        print(array);
        writer.println();
    }

    public void printLine() {
        writer.println();
    }

    public void printLine(Object...objects) {
        print(objects);
        writer.println();
    }

    public void print(char i) {
        writer.print(i);
    }

    public void printLine(char i) {
        writer.println(i);
    }

    public void printLine(char[] array) {
        writer.println(array);
    }

    public void printFormat(String format, Object...objects) {
        writer.printf(format, objects);
    }

    public void close() {
        writer.close();
    }

    public void flush() {
        writer.flush();
    }

    public void print(long i) {
        writer.print(i);
    }

    public void printLine(long i) {
        writer.println(i);
    }

    public void print(int i) {
        writer.print(i);
    }

    public void printLine(int i) {
        writer.println(i);
    }
}