#include <bits/stdc++.h>
using namespace std;
template <typename T>
void _R(T &x) {
  cin >> x;
}
void _R(int &x) { scanf("%d", &x); }
void _R(long long &x) { scanf("%" PRId64, &x); }
void _R(double &x) { scanf("%lf", &x); }
void _R(char &x) { scanf(" %c", &x); }
void _R(char *x) { scanf("%s", x); }
void R() {}
template <typename T, typename... U>
void R(T &head, U &...tail) {
  _R(head);
  R(tail...);
}
template <typename T>
void _W(const T &x) {
  cout << x;
}
void _W(const int &x) { printf("%d", x); }
template <typename T>
void _W(const vector<T> &x) {
  for (auto i = x.cbegin(); i != x.cend(); i++) {
    if (i != x.cbegin()) putchar(' ');
    _W(*i);
  }
}
void W() {}
template <typename T, typename... U>
void W(const T &head, const U &...tail) {
  _W(head);
  putchar(sizeof...(tail) ? ' ' : '\n');
  W(tail...);
}
const int N = 1e5 + 10;
const double pi = acos(-1);
struct P {
  double x, y;
  double len2() { return x * x + y * y; }
  double len() { return sqrt(len2()); }
} o, p[N];
P operator+(P a, P b) { return {a.x + b.x, a.y + b.y}; }
P operator-(P a, P b) { return {a.x - b.x, a.y - b.y}; }
P operator*(double a, P b) { return {a * b.x, a * b.y}; }
double dot(P a, P b) { return a.x * b.x + a.y * b.y; }
double area(double r) { return pi * r * r; }
int main() {
  int n;
  R(n, o.x, o.y);
  for (int i = 0; i < int(n); i++) R(p[i].x, p[i].y);
  double mx = 0;
  for (int i = 0; i < int(n); i++) mx = max(mx, (p[i] - o).len());
  double mi = 1e100;
  p[n] = p[0];
  for (int i = 0; i < int(n); i++) {
    mi = min(mi, (p[i] - o).len());
    double t = dot(p[i + 1] - p[i], o - p[i]) / (p[i + 1] - p[i]).len2();
    if (t < 0 || t > 1) continue;
    P ft = p[i] + t * (p[i + 1] - p[i]);
    mi = min(mi, (ft - o).len());
  }
  double ans = area(mx) - area(mi);
  printf("%.14f\n", ans);
  return 0;
}
