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.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.io.BufferedWriter;
import java.util.InputMismatchException;
import java.io.IOException;
import java.io.Writer;
import java.io.OutputStreamWriter;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 *
 * @author Junior Andrade
 */
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);
        TaskC solver = new TaskC();
        solver.solve(1, in, out);
        out.close();
    }

    static class TaskC {
        private double getArea(double ratio) {
            return (ratio * ratio * Math.PI);
        }

        public void solve(int testNumber, InputReader in, OutputWriter out) {
            int n = in.nextInt();
            Point[] p = new Point[n];
            double px = in.nextInt();
            double py = in.nextInt();
            Point pc = new Point(px, py);
            for (int i = 0; i < n; ++i) {
                double x, y;
                x = in.nextInt();
                y = in.nextInt();
                p[i] = new Point(x, y);
            }
            double maxR, minR;
            maxR = -10000000000000.;
            minR = 100000000000000.;
            for (int i = 0; i < n; ++i) {
                int nxt = (i + 1) % n;
                Segment l = new Segment(p[i], p[nxt]);
                double d = l.distance(pc);
                maxR = Math.max(maxR, p[i].distance(pc));
                minR = Math.min(minR, d);
            }
            out.printLine(getArea(maxR) - getArea(minR));
        }

    }

    static class Segment {
        public final Point a;
        public final Point b;
        private double distance = Double.NaN;
        private Line line = null;

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

        public double length() {
            if (Double.isNaN(distance))
                distance = a.distance(b);
            return distance;
        }

        public double distance(Point point) {
            double length = length();
            double left = point.distance(a);
            if (length < GeometryUtils.epsilon)
                return left;
            double right = point.distance(b);
            if (left * left > right * right + length * length)
                return right;
            if (right * right > left * left + length * length)
                return left;
            return point.distance(line());
        }

        public Line line() {
            if (line == null)
                line = a.line(b);
            return line;
        }

    }

    static 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 nextInt() {
            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 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;
        }

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

        }

    }

    static class GeometryUtils {
        public static double epsilon = 1e-8;

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

    }

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

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

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

    }

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


        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;
        }

    }

    static class Point {
        public final double x;
        public final double y;


        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);
        }


        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;
        }


        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);
        }

    }
}