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:
/*
 * Code Author: Jayesh Udhani
 * Dhirubhai Ambani Institute of Information and Communication Technology (DA-IICT ,Gandhinagar)
 * 2nd Year ICT BTECH Student
 */
import java.io.*;
import java.util.*;
public class MainC {
    public static double PointToLineSegmentDistance(double x1,double y1,double x2,double y2,double x,double y)
    {
        if(inRange(x1, y1, x2, y2, x, y))
        {
            double p,q,r;
            p=(double) (y2-y1);
            q=(double) x1-x2;
            r=(double)y1*(x2-x1)-(double)x1*(y2-y1);
            double dist=((x*p+y*q+r)*(x*p+y*q+r))/(p*p+q*q);
            return dist;
        }
        else
            return Math.min(calcDistance(x1, y1, x, y), calcDistance(x2, y2, x, y));
    }
    public static double calcDistance(double x1,double y1,double x2,double y2) {
        return (x2-x1)*(x2-x1)+(y2-y1)*(y2-y1);
    }
    public static boolean inRange(double start_x, double start_y, double end_x, double end_y, double point_x, double point_y) 
    {
        double dx = end_x - start_x;
        double dy = end_y - start_y;
        double innerProduct = (point_x - start_x)*dx + (point_y - start_y)*dy;
        return 0 <= innerProduct && innerProduct <= dx*dx + dy*dy;
    }
    public static boolean CheckConsecutive(int a,int b,int n)
    {
        if(a==(b+1)%n || b==(a+1)%n)
            return true;
        else return false;
    }
    static class Pair<F,S> 
    {
        private double first;
        private double second;
        public Pair(double i, double j) 
        { 
            this.setFirst(i);
            this.setSecond(j);
        }
        public double getFirst() { return first; }
        public double getSecond() { return second ;}
        public void setFirst(double first) 
        {
            this.first = first;
        }
        public void setSecond(double second) 
        {
            this.second = second;
        }
    }
    public static void main(String args[])
    {
        InputReader in = new InputReader(System.in);
        OutputStream outputStream = System.out;
        PrintWriter out = new PrintWriter(outputStream);
        //----------My Code Starts Here----------
        int n,i,h1=-1;
        double min=Double.MAX_VALUE,max=Double.MIN_VALUE,c1,c2;
        n=in.nextInt();
        c1=in.nextInt();
        c2=in.nextInt();
        ArrayList<Pair> al=new ArrayList<Pair>();
        for(i=0;i<n;i++)
        {
            al.add(new Pair<>(in.nextInt(),in.nextInt()));
            double d=calcDistance(al.get(i).first, al.get(i).second, c1, c2);
            if(d<min)
            {
                min=d;
                h1=i;
            }
            if(d>max)
                max=d;
        }
        for(i=1;i<n;i++)
            min=Math.min(min, PointToLineSegmentDistance(al.get(i).first, al.get(i).second, al.get(i-1).first, al.get(i-1).second,c1,c2));
        min=Math.min(min, PointToLineSegmentDistance(al.get(0).first, al.get(0).second, al.get(n-1).first, al.get(n-1).second, c1, c2));
        System.out.println(Math.PI*(max-min));
        out.close();
        //---------------The End———————————————————
    }
    static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream inputstream) {
            reader = new BufferedReader(new InputStreamReader(inputstream));
            tokenizer = null;
        }

        public String nextLine(){
            String fullLine=null;
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    fullLine=reader.readLine();
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
                return fullLine;
            }
            return fullLine;
        }
        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }
        public long nextLong() {
            return Long.parseLong(next());
        }
        public int nextInt() {
            return Integer.parseInt(next());
        }
    }
}