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.*;

public class A implements Runnable {

    private static final boolean ONLINE_JUDGE = System.getProperty("ONLINE_JUDGE") != null;

    private BufferedReader in;
    private PrintWriter out;
    private StringTokenizer tok = new StringTokenizer("");

    private void init() throws FileNotFoundException {
        Locale.setDefault(Locale.US);
        String fileName = "";
        if (ONLINE_JUDGE && fileName.isEmpty()) {
            in = new BufferedReader(new InputStreamReader(System.in));
            out = new PrintWriter(System.out);
        } else {
            if (fileName.isEmpty()) {
                in = new BufferedReader(new FileReader("input.txt"));
                out = new PrintWriter("output.txt");
            } else {
                in = new BufferedReader(new FileReader(fileName + ".in"));
                out = new PrintWriter(fileName + ".out");
            }
        }
    }

    String readString() {
        while (!tok.hasMoreTokens()) {
            try {
                tok = new StringTokenizer(in.readLine());
            } catch (Exception e) {
                return null;
            }
        }
        return tok.nextToken();
    }

    int readInt() {
        return Integer.parseInt(readString());
    }

    long readLong() {
        return Long.parseLong(readString());
    }

    double readDouble() {
        return Double.parseDouble(readString());
    }

    int[] readIntArray(int size) {
        int[] a = new int[size];
        for (int i = 0; i < size; i++) {
            a[i] = readInt();
        }
        return a;
    }

    public static void main(String[] args) {
        //new Thread(null, new _Solution(), "", 128 * (1L << 20)).start();
        new A().run();
    }

    long timeBegin, timeEnd;

    void time() {
        timeEnd = System.currentTimeMillis();
        System.err.println("Time = " + (timeEnd - timeBegin));
    }

    @Override
    public void run() {
        try {
            timeBegin = System.currentTimeMillis();
            init();
            solve();
            out.close();
            time();
        } catch (Exception e) {
            e.printStackTrace();
            System.exit(-1);
        }
    }

    long getDistSqr(int x1, int y1, int x2, int y2) {
        long dx = x1 - x2;
        long dy = y1 - y2;
        return dx * dx + dy * dy;
    }

    private void solve() throws IOException {
        int n = readInt();
        int px = readInt();
        int py = readInt();
        int[] x = new int[n];
        int[] y = new int[n];
        for (int i = 0; i < n; i++) {
            x[i] = readInt();
            y[i] = readInt();
        }
        long RSquared = 0;
        double rSquared = Long.MAX_VALUE;
        for (int i = 0; i < n; i++) {
            RSquared = Math.max(RSquared, getDistSqr(px, py, x[i], y[i]));
        }
        for (int i = 0; i < n; i++) {
            int j = (i + 1) % n;
            long A1 = y[i] - y[j];
            long B1 = x[j] - x[i];
            long C1 = -A1 * x[i] - B1 * y[i];

            long A2 = -B1;
            long B2 = A1;
            long C2 = -A2 * px - B2 * py;

            long det = A1 * B2 - B1 * A2;
            double intersectionX = -1.0 * (C1 * B2 - B1 * C2) / det;
            double intersectionY = -1.0 * (A1 * C2 - A2 * C1) / det;

            if (inside(x[i], y[i], x[j], y[j], intersectionX, intersectionY)) {
                double dx = px - intersectionX;
                double dy = py - intersectionY;
                rSquared = Math.min(rSquared, dx * dx + dy * dy);
            } else {
                rSquared = Math.min(rSquared, getDistSqr(x[i], y[i], px, py));
                rSquared = Math.min(rSquared, getDistSqr(x[j], y[j], px, py));
            }
        }
        out.printf("%.12f", Math.PI * (RSquared - rSquared));
    }

    final double eps = 1e-8;

    boolean inside(int x1, int y1, int x2, int y2, double x, double y) {
        return (Math.min(x1, x2) <= x + eps && Math.max(x1, x2) + eps >= x
                && Math.min(y1, y2) <= y + eps && Math.max(y1, y2) + eps >= y);
    }
}