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 CPP):

Solution:
#include <bits/stdc++.h>
using namespace std;
const int maxn = 1e5 + 50;
const double eps = 1e-10;
const int max_index = 62;
const int inf = 0x3f3f3f3f;
const int MOD = 1e9 + 7;
const double PI = 3.14159265358979323;
inline int read() {
  char c = getchar();
  while (!isdigit(c)) c = getchar();
  int x = 0;
  while (isdigit(c)) {
    x = x * 10 + c - '0';
    c = getchar();
  }
  return x;
}
struct Point {
  double x, y;
  Point(double x = 0, double y = 0) : x(x), y(y) {}
};
Point operator+(const Point& A, const Point& B) {
  return Point(A.x + B.x, A.y + B.y);
}
Point operator-(const Point& A, const Point& B) {
  return Point(A.x - B.x, A.y - B.y);
}
Point operator*(const Point& A, double p) { return Point(A.x * p, A.y * p); }
Point operator/(const Point& A, double p) { return Point(A.x / p, A.y / p); }
bool operator<(const Point& a, const Point& b) {
  return a.x < b.x || (a.x == b.x && a.y < b.y);
}
int dcmp(double x) {
  if (fabs(x) < eps) return 0;
  return x < 0 ? -1 : 1;
}
bool operator==(const Point& a, const Point& b) {
  return !dcmp(a.x - b.x) && !dcmp(a.y - b.y);
}
double Dot(const Point& A, const Point& B) { return A.x * B.x + A.y * B.y; }
double Cross(const Point& A, const Point& B) { return A.x * B.y - A.y * B.x; }
double Length(const Point& A) { return sqrt(Dot(A, A)); }
double Angle(const Point& A, const Point& B) {
  return acos(Dot(A, B) / Length(A) / Length(B));
}
double Area2(const Point& A, const Point& B, const Point& C) {
  return Cross(B - A, C - A);
}
Point Rotate(const Point& A, double rad) {
  return Point(A.x + cos(rad) - A.y * sin(rad),
               A.x * sin(rad) + A.y * cos(rad));
}
Point Normal(const Point& A) {
  double L = Length(A);
  return Point(-A.y / L, A.x / L);
}
Point GetLineIntersection(const Point& P, const Point& v, const Point& Q,
                          const Point& w) {
  Point u = P - Q;
  double t = Cross(w, u) / Cross(v, w);
  return P + v * t;
}
double DistanceToLine(const Point& P, const Point& A, const Point& B) {
  Point v1 = B - A, v2 = P - A;
  return fabs(Cross(v1, v2) / Length(v1));
}
double DistanceToSegment(const Point& P, const Point& A, const Point& B) {
  if (A == B) return Length(P - A);
  Point v1 = B - A, v2 = P - A, v3 = P - B;
  if (dcmp(Dot(v1, v2)) < 0) return Length(v2);
  if (dcmp(Dot(v1, v3)) > 0) return Length(v3);
  return fabs(Cross(v1, v2) / Length(v1));
}
Point GetLineProjection(const Point& P, const Point& A, const Point& B) {
  Point v = B - A;
  return A + v * (Dot(v, P - A) / Dot(v, v));
}
bool SegmentProperIntersection(const Point& a1, const Point& a2,
                               const Point& b1, const Point& b2) {
  double c1 = Cross(a2 - a1, b1 - a1), c2 = Cross(a2 - a1, b2 - a1),
         c3 = Cross(b2 - b1, a1 - b1), c4 = Cross(b2 - b1, a2 - b1);
  return dcmp(c1) * dcmp(c2) < 0 && dcmp(c3) * dcmp(c4) < 0;
}
bool OnSegment(const Point& p, const Point& a1, const Point& a2) {
  return !dcmp(Cross(a1 - p, a2 - p)) && dcmp(Dot(a1 - p, a2 - p)) < 0;
}
double PolygonArea(Point* p, int n) {
  double area = 0;
  for (int i = 1; i < n - 1; i++) area += Cross(p[i] - p[0], p[i + 1] - p[0]);
  return area / 2;
}
Point ReadPoint() {
  Point res;
  scanf("%lf%lf", &res.x, &res.y);
  return res;
}
int n;
Point P, p[maxn];
int main() {
  scanf("%d", &n);
  P = ReadPoint();
  double l = 10000000, r = -1;
  for (int i = 1; i <= n; i++) {
    p[i] = ReadPoint();
    r = max(r, Length(p[i] - P));
  }
  p[n + 1] = p[1];
  for (int i = 1; i <= n; i++) {
    l = min(l, DistanceToSegment(P, p[i], p[i + 1]));
  }
  printf("%.10f\n", PI * (r * r - l * l));
  return 0;
}