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.InputStream;
import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.BufferedReader;
import java.io.PrintWriter;
import java.util.StringTokenizer;
import java.io.InputStreamReader;
import java.io.IOException;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 *
 * @author Artem Gilmudinov
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Reader in = new Reader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        TaskC solver = new TaskC();
        solver.solve(1, in, out);
        out.close();
    }

    static class TaskC {
        public void solve(int testNumber, Reader in, PrintWriter out) {
            int n = in.ni();
            Point center = new Point(in.nd(), in.nd());
            Point[] points = new Point[n];
            for (int i = 0; i < n; i++) {
                points[i] = new Point(in.nd(), in.nd());
                points[i].x -= center.x;
                points[i].y -= center.y;
            }
            center = new Point(0, 0);
            double maxDist, minDist;
            minDist = Long.MAX_VALUE;
            maxDist = 0;
            for (int i = 0; i < n; i++) {
                Point f = points[i];
                Point s = points[(i + 1) % n];
                Point buf = f.clone();
                buf.x -= s.x;
                buf.y -= s.y;
                double temp = buf.x;
                buf.x = -buf.y;
                buf.y = temp;
                Line line1 = GeomUtils.points2Line(center, buf);
                Line line2 = GeomUtils.points2Line(f, s);
                Point intersection = intersect(line1, line2);
                if (GeomUtils.onSegment(f, s, intersection)) {
                    minDist = Math.min(minDist, GeomUtils.dist(intersection));
                }
                minDist = Math.min(minDist, GeomUtils.dist(f));
                minDist = Math.min(minDist, GeomUtils.dist(s));
                maxDist = Math.max(maxDist, GeomUtils.dist(f));
                maxDist = Math.max(maxDist, GeomUtils.dist(s));
            }
            double s1 = Math.PI * maxDist * maxDist;
            double s2 = Math.PI * minDist * minDist;
            out.println(s1 - s2);
        }

        double det(double a, double b, double c, double d) {
            return a * d - b * c;
        }

        Point intersect(Line m, Line n) {
            double zn = det(m.a, m.b, n.a, n.b);
            return new Point(-det(m.c, m.b, n.c, n.b) / zn, -det(m.a, m.c, n.a, n.c) / zn);
        }

    }

    static class Reader {
        private BufferedReader in;
        private StringTokenizer st = new StringTokenizer("");
        private String delim = " ";

        public Reader(InputStream in) {
            this.in = new BufferedReader(new InputStreamReader(in));
        }

        public String next() {
            if (!st.hasMoreTokens()) {
                st = new StringTokenizer(rl());
            }
            return st.nextToken(delim);
        }

        public String rl() {
            try {
                return in.readLine();
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
        }

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

        public double nd() {
            return Double.parseDouble(next());
        }

    }

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

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

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

        public boolean equals(Object obj) {
            Point p = (Point) obj;
            return Math.abs(this.x - p.x) <= GeomUtils.eps && Math.abs(this.y - p.y) <= GeomUtils.eps;
        }

        public Point clone() {
            return new Point(x, y);
        }

    }

    static class GeomUtils {
        public static final double eps = 1e-15;

        public static double dist(Point p1) {
            return Math.sqrt(p1.x * p1.x + p1.y * p1.y);
        }

        public static boolean onSegment(Point p1, Point p2, Point p3) {
            return Math.min(p1.x, p2.x) <= p3.x && p3.x <= Math.max(p1.x, p2.x) &&
                    Math.min(p1.y, p2.y) <= p3.y && p3.y <= Math.max(p1.y, p2.y);
        }

        public static Line points2Line(Point p1, Point p2) {
            if (p1.equals(p2)) {
                return null;
            }
            if (Math.abs(p1.x - p2.x) <= GeomUtils.eps) {
                return new Line(1, 0, -p1.x);
            }
            if (Math.abs(p1.y - p2.y) <= GeomUtils.eps) {
                return new Line(0, 1, -p1.y);
            }
            return new Line(p1.y - p2.y, p2.x - p1.x, p1.x * p2.y - p1.y * p2.x);
        }

    }

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

        public Line(double a, double b, double c) {
            this.a = a;
            this.b = b;
            this.c = c;
        }

        public String toString() {
            return this.a + " " + this.b + " " + this.c;
        }

    }
}