Problem: Peter got a new snow blower as a New Year present. Of course, Peter decided to try it immediately. After reading the instructions he realized that it does not work like regular snow blowing machines. In order to make it work, you need to tie it to some point that it does not cover, and then switch it on. As a result it will go along a circle around this point and will remove all the snow from its path.

Formally, we assume that Peter's machine is a polygon on a plane. Then, after the machine is switched on, it will make a circle around the point to which Peter tied it (this point lies strictly outside the polygon). That is, each of the points lying within or on the border of the polygon will move along the circular trajectory, with the center of the circle at the point to which Peter tied his machine.

Peter decided to tie his car to point P and now he is wondering what is the area of ​​the region that will be cleared from snow. Help him.

Input

The first line of the input contains three integers — the number of vertices of the polygon n (<image>), and coordinates of point P.

Each of the next n lines contains two integers — coordinates of the vertices of the polygon in the clockwise or counterclockwise order. It is guaranteed that no three consecutive vertices lie on a common straight line.

All the numbers in the input are integers that do not exceed 1 000 000 in their absolute value.

Output

Print a single real value number — the area of the region that will be cleared. Your answer will be considered correct if its absolute or relative error does not exceed 10 - 6. 

Namely: let's assume that your answer is a, and the answer of the jury is b. The checker program will consider your answer correct, if <image>.

Examples

Input

3 0 0
0 1
-1 2
1 2


Output

12.566370614359172464


Input

4 1 -1
0 0
1 2
2 0
1 1


Output

21.991148575128551812

Note

In the first sample snow will be removed from that area:

<image>

Solution (in JAVA):

Solution:
import java.io.*;
import java.util.ArrayList;
import java.util.StringTokenizer;


public class Main {

    private static final double EPS = 1e-7;

    public static void main(String[] args) throws Exception {
        FastScanner fastScanner = new FastScanner(System.in);
        PrintWriter printWriter = new PrintWriter(System.out);
        Main main = new Main();
        main.solveC(fastScanner, printWriter);
        printWriter.close();

    }


    public void solveC(FastScanner scanner, PrintWriter writer) {
        int n = scanner.nextInt();
        long cX = scanner.nextLong();
        long cY = scanner.nextLong();
        Point centre = new Point(cX, cY);
        double max = Long.MIN_VALUE;
        double min = Long.MAX_VALUE;

        ArrayList<Point> points = new ArrayList<>((int) n);


        for (int i = 0; i < n; i++) {
            long x = scanner.nextLong();
            long y = scanner.nextLong();
            Point point = new Point(x, y);
            points.add(point);
            double distanceSquare = distanceSquare(point, centre);
            if (distanceSquare - max > EPS) max = distanceSquare;
            if (min - distanceSquare > EPS) min = distanceSquare;
        }

        for (int i = 1; i < n; i++) {
            double distanceSquare = lineToPointDist(points.get(i - 1), points.get(i), centre);
            if (min - distanceSquare > EPS) min = distanceSquare;
        }

        double distanceSquare = lineToPointDist(points.get(n - 1), points.get(0), centre);
        if (min - distanceSquare > EPS) min = distanceSquare;

        double area = Math.PI * (max - min);
        writer.write(area + "\n");

    }

    //distance from line ab to c squared
    public double lineToPointDist(Point a, Point b, Point c) {
        double cross = cross(a, b, c);
        double distSquare = cross * cross / distanceSquare(a, b);
        long dotB = dot(a, b, c);
        if (dotB > 0) return distanceSquare(b, c);
        long dotA = dot(b, a, c);
        if (dotA > 0) return distanceSquare(a, c);
        return Math.abs(distSquare);
    }

    public long cross(Point a, Point b, Point c) {
        Point vectorAB = new Point(b.x - a.x, b.y - a.y);
        Point vectorAC = new Point(c.x - a.x, c.y - a.y);

        long cross = vectorAB.x * vectorAC.y - vectorAB.y * vectorAC.x;
        return cross;
    }

    //dot of ab and bc
    public long dot(Point a, Point b, Point c) {
        Point vectorAB = new Point(b.x - a.x, b.y - a.y);
        Point vectorBC = new Point(c.x - b.x, c.y - b.y);
        long dot = vectorAB.x * vectorBC.x + vectorAB.y * vectorBC.y;
        return dot;
    }

    public double distanceSquare(Point a, Point b) {
        long diffx = a.x - b.x;
        long diffy = a.y - b.y;
        return diffx * diffx + diffy * diffy;
    }

    static class Point {
        long x, y;

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


    static class FastScanner {
        private BufferedReader reader = null;
        private StringTokenizer tokenizer = null;

        public FastScanner(InputStream in) {
            reader = new BufferedReader(new InputStreamReader(in));
            tokenizer = null;
        }

        public String next() {
            if (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        public String nextLine() {
            if (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    return reader.readLine();
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }

            return tokenizer.nextToken("\n");
        }

        public long nextLong() {
            return Long.parseLong(next());
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

    }


}