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.util.*;
import java.io.*;

public class Main {
	public static void main(String[] args) throws IOException {
		Scanner sc = new Scanner(System.in);
		PrintWriter out = new PrintWriter(System.out);
		int n=sc.nextInt();
		Point c = new Point(sc.nextInt(), sc.nextInt());
		Point[] arr = new Point[n];
		double INF = 1e16;
		double minr = INF, maxr=  -INF;
		for(int i=0;i<n;i++) {
			arr[i]=  new Point(sc.nextInt(), sc.nextInt());
			maxr = Math.max(maxr, arr[i].dist(c));
		}
		for(int i=0;i<n;i++)
			minr = Math.min(minr, Point.distToLineSegment(c, arr[i], arr[(i+1)%n]));
		out.println(Math.PI * (maxr*maxr - minr*minr));
		out.close();
	}

	static class Vector {

		double x, y; 

		Vector(double a, double b) { x = a; y = b; }

		Vector(Point a, Point b) { this(b.x - a.x, b.y - a.y); }

		Vector scale(double s) { return new Vector(x * s, y * s); }              //s is a non-negative value

		double dot(Vector v) { return (x * v.x + y * v.y); }

		double cross(Vector v) { return x * v.y - y * v.x; }

		double norm2() { return x * x + y * y; }

		Vector reverse() { return new Vector(-x, -y); }

		Vector normalize() 
		{ 
			double d = Math.sqrt(norm2());
			return scale(1 / d);
		}		
	}
	static class Point implements Comparable<Point>{

		static final double EPS = 1e-9;

		double x, y;                  

		Point(double a, double b) { x = a; y = b; }  
		
		public int compareTo(Point p)
		{
			if(Math.abs(x - p.x) > EPS) return x > p.x ? 1 : -1;
			if(Math.abs(y - p.y) > EPS) return y > p.y ? 1 : -1;
			return 0;
		}
		
		public double dist(Point p) { return Math.sqrt(sq(x - p.x) + sq(y - p.y)); }
		
		static double sq(double x) { return x * x; }
		
		Point rotate(double angle)
		{
			double c = Math.cos(angle), s = Math.sin(angle);
			return new Point(x * c - y * s, x * s + y * c);
		}
		// for integer points and rotation by 90 (counterclockwise) : swap x and y, negate x
		
		Point rotate(double theta, Point p)			//rotate around p
		{
			Vector v = new Vector(p, new Point(0, 0));
			return translate(v).rotate(theta).translate(v.reverse());
		}
		
		Point translate(Vector v) { return new Point(x + v.x , y + v.y); }
		
		boolean between(Point p, Point q)
		{
			return x < Math.max(p.x, q.x) + EPS && x + EPS > Math.min(p.x, q.x)
					&& y < Math.max(p.y, q.y) + EPS && y + EPS > Math.min(p.y, q.y);
		}
		
		//returns true if it is on the line defined by a and b
		boolean onLine(Point a, Point b) 
		{
			if(a.compareTo(b) == 0) return compareTo(a) == 0;
			return Math.abs(new Vector(a, b).cross(new Vector(a, this))) < EPS;
		}
		
		boolean onSegment(Point a, Point b)
		{
			if(a.compareTo(b) == 0) return compareTo(a) == 0;
			return onRay(a, b) && onRay(b, a);
		}
		
		//returns true if it is on the ray whose start point is a and passes through b
		boolean onRay(Point a, Point b)
		{
			if(a.compareTo(b) == 0) return compareTo(a) == 0;
			return new Vector(a, b).normalize().equals(new Vector(a, this).normalize());	//implement equals()
		}
		
		// returns true if it is on the left side of Line pq
		// add EPS to LHS if on-line points are accepted
		static boolean ccw(Point p, Point q, Point r)
		{
			return new Vector(p, q).cross(new Vector(p, r)) > 0;
		}
		
		static boolean collinear(Point p, Point q, Point r)
		{
			return Math.abs(new Vector(p, q).cross(new Vector(p, r))) < EPS;
		}
		
		static double angle(Point a, Point o, Point b)  // angle AOB
		{
			Vector oa = new Vector(o, a), ob = new Vector(o, b);
			return Math.acos(oa.dot(ob) / Math.sqrt(oa.norm2() * ob.norm2()));
		}
		
		static double distToLine(Point p, Point a, Point b) //distance between point p and a line defined by points a, b (a != b)
		{
			if(a.compareTo(b) == 0) return p.dist(a);
			// formula: c = a + u * ab
			Vector ap = new Vector(a, p), ab = new Vector(a, b);
			double u = ap.dot(ab) / ab.norm2();
			Point c = a.translate(ab.scale(u)); 
			return p.dist(c);
		}
		// Another way: find closest point and calculate the distance between it and p

		static double distToLineSegment(Point p, Point a, Point b) 
		{
			Vector ap = new Vector(a, p), ab = new Vector(a, b);
			double u = ap.dot(ab) / ab.norm2();
			if (u < 0.0) return p.dist(a);
			if (u > 1.0) return p.dist(b);        
			return distToLine(p, a, b); 
		}
		// Another way: find closest point and calculate the distance between it and p
	}


	static class Scanner {
		StringTokenizer st;
		BufferedReader br;

		public Scanner(InputStream s) {
			br = new BufferedReader(new InputStreamReader(s));
		}

		public Scanner(String s) throws FileNotFoundException {
			br = new BufferedReader(new FileReader(s));
		}

		public String next() throws IOException {
			while (st == null || !st.hasMoreTokens())
				st = new StringTokenizer(br.readLine());
			return st.nextToken();
		}

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

		public int[] nextIntArray(int n) throws IOException {
			int[] ans = new int[n];
			for (int i = 0; i < n; i++)
				ans[i] = nextInt();
			return ans;
		}

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

		public String nextLine() throws IOException {
			return br.readLine();
		}

		public double nextDouble() throws IOException {
			return Double.parseDouble(next());
		}

		public boolean ready() throws IOException {
			return br.ready();
		}

	}
}