#include <bits/stdc++.h>
using namespace std;
double esp = 1e-11;
#pragma comment(linker, "/STACK:1024000000,1024000000")
const double PI = acos(-1.0);
const long long int INF = 0x3f3f3f3f3f3f3f3f;
const long long int MOD = 1000000007;
const int maxn = 100500;
struct point {
  double x, y;
  point() { x = y = 0; }
  point(double x, double y) {
    this->x = x;
    this->y = y;
  }
  point operator*(const double &a) { return point(a * x, a * y); }
  point operator/(const double &a) { return point(x / a, y / a); }
  double operator*(const point &a) { return a.x * x + a.y * y; }
  point operator+(const point &a) { return point(x + a.x, y + a.y); }
  point operator-(const point &a) { return point(x - a.x, y - a.y); }
  bool operator<(const point &a) const {
    return x < a.x - esp || (abs(x - a.x) < esp && y < a.y - esp);
  }
};
point operator*(double const &a, point const &b) {
  return point(a * b.x, a * b.y);
}
double cross(point a, point b) { return a.x * b.y - a.y * b.x; }
double leng(point a) { return sqrt(a.x * a.x + a.y * a.y); }
vector<point> m;
double dmax = 0, dmin = INF * 1.0;
void f(double ans) {
  dmax = max(dmax, ans);
  dmin = min(dmin, ans);
}
int main() {
  int n;
  scanf("%d", &n);
  int u, v;
  m.clear();
  scanf("%d%d", &u, &v);
  point p(u, v);
  point tem;
  dmax = 0, dmin = INF;
  double s1, s2, s3, coth;
  for (int x = 1; x <= n; x++) {
    scanf("%d%d", &u, &v);
    tem.x = u;
    tem.y = v;
    m.push_back(tem);
    f(leng(tem - p));
  }
  point a, b;
  for (int x = 1; x < n; x++) {
    a = m[x - 1];
    b = m[x];
    s1 = leng(b - a);
    s2 = leng(p - b);
    s3 = leng(p - a);
    coth = s1 * s1 + s3 * s3 - s2 * s2;
    coth /= (2.0 * s1 * s3);
    if (s3 * coth > -esp && s3 * coth < s1 + esp) f(s3 * sqrt(1 - coth * coth));
  }
  a = m[0];
  b = m[n - 1];
  s1 = leng(b - a);
  s2 = leng(p - b);
  s3 = leng(p - a);
  coth = s1 * s1 + s3 * s3 - s2 * s2;
  coth /= (2.0 * s1 * s3);
  if (s3 * coth > -esp && s3 * coth < s1 + esp) f(s3 * sqrt(1 - coth * coth));
  double ans = PI * dmax * dmax;
  ans -= PI * dmin * dmin;
  printf("%.7f\n", ans);
  return 0;
}
