#include <bits/stdc++.h>
#pragma GCC optimize("O3")
#pragma GCC target("avx2,avx")
#pragma GCC optimize("unroll-loops")
using namespace std;
template <class T>
using pq = priority_queue<T>;
template <class T>
using pqg = priority_queue<T, vector<T>, greater<T>>;
int scan() { return getchar(); }
void scan(int &a) { cin >> a; }
void scan(long long &a) { cin >> a; }
void scan(char &a) { cin >> a; }
void scan(double &a) { cin >> a; }
void scan(long double &a) { cin >> a; }
void scan(string &a) { cin >> a; }
template <class T>
void scan(vector<T> &);
template <class T>
void scan(vector<T> &a) {
  for (auto &i : a) scan(i);
}
template <class T>
void scan(T &a) {
  cin >> a;
}
void IN() {}
template <class Head, class... Tail>
void IN(Head &head, Tail &...tail) {
  scan(head);
  IN(tail...);
}
string stin() {
  string s;
  cin >> s;
  return s;
}
template <class T, class S>
inline bool chmax(T &a, S b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
template <class T, class S>
inline bool chmin(T &a, S b) {
  if (a > b) {
    a = b;
    return 1;
  }
  return 0;
}
vector<int> iota(int n) {
  vector<int> a(n);
  iota(begin(a), end(a), 0);
  return a;
}
template <class T>
void UNIQUE(vector<T> &x) {
  sort(begin(x), end(x));
  x.erase(unique(begin(x), end(x)), x.end());
}
int in() {
  int x;
  cin >> x;
  return x;
}
long long lin() {
  unsigned long long x;
  cin >> x;
  return x;
}
void print() { putchar(' '); }
void print(bool a) { cout << a; }
void print(int a) { cout << a; }
void print(long long a) { cout << a; }
void print(char a) { cout << a; }
void print(string &a) { cout << a; }
void print(double a) { cout << a; }
template <class T>
void print(const vector<T> &);
template <class T, size_t size>
void print(const array<T, size> &);
template <class T, class L>
void print(const pair<T, L> &p);
template <class T, size_t size>
void print(const T (&)[size]);
template <class T>
void print(const vector<T> &a) {
  if (a.empty()) return;
  print(a[0]);
  for (auto i = a.begin(); ++i != a.end();) {
    cout << " ";
    print(*i);
  }
  cout << endl;
}
template <class T>
void print(const deque<T> &a) {
  if (a.empty()) return;
  print(a[0]);
  for (auto i = a.begin(); ++i != a.end();) {
    cout << " ";
    print(*i);
  }
}
template <class T, size_t size>
void print(const array<T, size> &a) {
  print(a[0]);
  for (auto i = a.begin(); ++i != a.end();) {
    cout << " ";
    print(*i);
  }
}
template <class T, class L>
void print(const pair<T, L> &p) {
  cout << '(';
  print(p.first);
  cout << ",";
  print(p.second);
  cout << ')';
}
template <class T>
void print(set<T> &x) {
  for (auto e : x) print(e), cout << " ";
  cout << endl;
}
template <class T>
void print(multiset<T> &x) {
  for (auto e : x) print(e), cout << " ";
  cout << endl;
}
template <class T, size_t size>
void print(const T (&a)[size]) {
  print(a[0]);
  for (auto i = a; ++i != end(a);) {
    cout << " ";
    print(*i);
  }
}
template <class T>
void print(const T &a) {
  cout << a;
}
int out() {
  putchar('\n');
  return 0;
}
template <class T>
int out(const T &t) {
  print(t);
  putchar('\n');
  return 0;
}
template <class Head, class... Tail>
int out(const Head &head, const Tail &...tail) {
  print(head);
  putchar(' ');
  out(tail...);
  return 0;
}
long long gcd(long long a, long long b) {
  while (b) {
    long long c = b;
    b = a % b;
    a = c;
  }
  return a;
}
long long lcm(long long a, long long b) {
  if (!a || !b) return 0;
  return a * b / gcd(a, b);
}
vector<pair<long long, long long>> factor(long long x) {
  vector<pair<long long, long long>> ans;
  for (long long i = 2; i * i <= x; i++)
    if (x % i == 0) {
      ans.push_back({i, 1});
      while ((x /= i) % i == 0) ans.back().second++;
    }
  if (x != 1) ans.push_back({x, 1});
  return ans;
}
template <class T>
vector<T> divisor(T x) {
  vector<T> ans;
  for (T i = 1; i * i <= x; i++)
    if (x % i == 0) {
      ans.push_back(i);
      if (i * i != x) ans.push_back(x / i);
    }
  return ans;
}
template <typename T>
void zip(vector<T> &x) {
  vector<T> y = x;
  sort(begin(y), end(y));
  for (int i = 0; i < x.size(); ++i) {
    x[i] = distance((y).begin(), lower_bound(begin(y), end(y), (x[i])));
  }
}
int popcount(long long x) { return __builtin_popcountll(x); }
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
int rnd(int n) { return uniform_int_distribution<int>(0, n - 1)(rng); }
long long rndll(long long n) {
  return uniform_int_distribution<long long>(0, n - 1)(rng);
}
template <typename T>
void shuffle(vector<T> &v) {
  for (long long i = v.size() - 1; i >= 1; --i) {
    swap(v[i], v[rnd(i)]);
  }
}
vector<string> YES{"NO", "YES"};
vector<string> Yes{"No", "Yes"};
vector<string> yes{"no", "yes"};
template <class... T>
void err(const T &...) {}
template <typename T>
struct edge {
  int from, to;
  T cost;
  int id;
  edge(int to, T cost) : from(-1), to(to), cost(cost) {}
  edge(int from, int to, T cost) : from(from), to(to), cost(cost) {}
  edge(int from, int to, T cost, int id)
      : from(from), to(to), cost(cost), id(id) {}
  edge &operator=(const int &x) {
    to = x;
    return *this;
  }
  operator int() const { return to; }
};
template <typename T>
using Edges = vector<edge<T>>;
struct Graph : vector<vector<int>> {
  using vector<vector<int>>::vector;
  Graph(int n, int m) : vector(n) { read(m); }
  inline void add(int a, int b, bool directed = false) {
    (*this)[a].emplace_back(b);
    if (!directed) (*this)[b].emplace_back(a);
  }
  void read(int n = -1, int offset = 1, bool directed = false) {
    if (n == -1) n = this->size() - 1;
    int a, b;
    while (n--) {
      cin >> a >> b;
      Graph::add(a - offset, b - offset, directed);
    }
  }
};
template <typename T>
struct WeightedGraph : vector<Edges<T>> {
  using vector<Edges<T>>::vector;
  inline void add(int a, int b, T c, bool directed = false) {
    (*this)[a].emplace_back(b, c);
    if (!directed) (*this)[b].emplace_back(a, c);
  }
  void read(int n = -1, int offset = 1) {
    if (n == -1) n = this->size() - 1;
    int a, b;
    T c;
    while (n--) {
      cin >> a >> b >> c;
      WeightedGraph::add(a - offset, b - offset, c);
    }
  }
};
struct Setup_io {
  Setup_io() {
    ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0);
    cout << fixed << setprecision(15);
  }
} setup_io;
using Real = double;
using Point = complex<Real>;
const Real EPS = 1e-8, PI = acos(-1);
inline bool eq(Real a, Real b) { return fabs(b - a) < EPS; }
Point operator*(const Point &p, const Real &d) {
  return Point(real(p) * d, imag(p) * d);
}
istream &operator>>(istream &is, Point &p) {
  Real a, b;
  is >> a >> b;
  p = Point(a, b);
  return is;
}
ostream &operator<<(ostream &os, Point &p) {
  return os << fixed << setprecision(10) << p.real() << " " << p.imag();
}
Point rotate(Real theta, const Point &p) {
  return Point(cos(theta) * p.real() - sin(theta) * p.imag(),
               sin(theta) * p.real() + cos(theta) * p.imag());
}
Real radian_to_degree(Real r) { return (r * 180.0 / PI); }
Real degree_to_radian(Real d) { return (d * PI / 180.0); }
Real get_angle(const Point &a, const Point &b, const Point &c) {
  const Point v(b - a), w(c - b);
  Real alpha = atan2(v.imag(), v.real()), beta = atan2(w.imag(), w.real());
  if (alpha > beta) swap(alpha, beta);
  Real theta = (beta - alpha);
  return min(theta, 2 * acos(-1) - theta);
}
namespace std {
bool operator<(const Point &a, const Point &b) {
  return a.real() != b.real() ? a.real() < b.real() : a.imag() < b.imag();
}
}  // namespace std
struct Line {
  Point a, b;
  Line() = default;
  Line(Point a, Point b) : a(a), b(b) {}
  Line(Real A, Real B, Real C) {
    if (eq(A, 0))
      a = Point(0, C / B), b = Point(1, C / B);
    else if (eq(B, 0))
      b = Point(C / A, 0), b = Point(C / A, 1);
    else
      a = Point(0, C / B), b = Point(C / A, 0);
  }
  friend ostream &operator<<(ostream &os, Line &p) {
    return os << p.a << " to " << p.b;
  }
  friend istream &operator>>(istream &is, Line &a) { return is >> a.a >> a.b; }
};
struct Segment : Line {
  Segment() = default;
  Segment(Point a, Point b) : Line(a, b) {}
};
struct Circle {
  Point p;
  Real r;
  Circle() = default;
  Circle(Point p, Real r) : p(p), r(r) {}
};
using Points = vector<Point>;
using Polygon = vector<Point>;
using Segments = vector<Segment>;
using Lines = vector<Line>;
using Circles = vector<Circle>;
Real cross(const Point &a, const Point &b) {
  return real(a) * imag(b) - imag(a) * real(b);
}
Real dot(const Point &a, const Point &b) {
  return real(a) * real(b) + imag(a) * imag(b);
}
int ccw(const Point &a, Point b, Point c) {
  b = b - a, c = c - a;
  if (cross(b, c) > EPS) return +1;
  if (cross(b, c) < -EPS) return -1;
  if (dot(b, c) < 0) return +2;
  if (norm(b) < norm(c)) return -2;
  return 0;
}
bool parallel(const Line &a, const Line &b) {
  return eq(cross(a.b - a.a, b.b - b.a), 0.0);
}
bool orthogonal(const Line &a, const Line &b) {
  return eq(dot(a.a - a.b, b.a - b.b), 0.0);
}
Point projection(const Line &l, const Point &p) {
  double t = dot(p - l.a, l.a - l.b) / norm(l.a - l.b);
  return l.a + (l.a - l.b) * t;
}
Point projection(const Segment &l, const Point &p) {
  double t = dot(p - l.a, l.a - l.b) / norm(l.a - l.b);
  return l.a + (l.a - l.b) * t;
}
Point reflection(const Line &l, const Point &p) {
  return p + (projection(l, p) - p) * 2.0;
}
bool intersect(const Line &l, const Point &p) {
  return abs(ccw(l.a, l.b, p)) != 1;
}
bool intersect(const Line &l, const Line &m) {
  return abs(cross(l.b - l.a, m.b - m.a)) > EPS ||
         abs(cross(l.b - l.a, m.b - l.a)) < EPS;
}
bool intersect(const Segment &s, const Point &p) {
  return ccw(s.a, s.b, p) == 0;
}
bool intersect(const Line &l, const Segment &s) {
  return cross(l.b - l.a, s.a - l.a) * cross(l.b - l.a, s.b - l.a) < EPS;
}
Real distance(const Line &l, const Point &p);
bool intersect(const Circle &c, const Line &l) {
  return distance(l, c.p) <= c.r + EPS;
}
bool intersect(const Circle &c, const Point &p) {
  return abs(abs(p - c.p) - c.r) < EPS;
}
bool intersect(const Segment &s, const Segment &t) {
  return ccw(s.a, s.b, t.a) * ccw(s.a, s.b, t.b) <= 0 &&
         ccw(t.a, t.b, s.a) * ccw(t.a, t.b, s.b) <= 0;
}
int intersect(const Circle &c, const Segment &l) {
  if (norm(projection(l, c.p) - c.p) - c.r * c.r > EPS) return 0;
  auto d1 = abs(c.p - l.a), d2 = abs(c.p - l.b);
  if (d1 < c.r + EPS && d2 < c.r + EPS) return 0;
  if (d1 < c.r - EPS && d2 > c.r + EPS || d1 > c.r + EPS && d2 < c.r - EPS)
    return 1;
  const Point h = projection(l, c.p);
  if (dot(l.a - h, l.b - h) < 0) return 2;
  return 0;
}
int intersect(Circle c1, Circle c2) {
  if (c1.r < c2.r) swap(c1, c2);
  Real d = abs(c1.p - c2.p);
  if (c1.r + c2.r < d) return 4;
  if (eq(c1.r + c2.r, d)) return 3;
  if (c1.r - c2.r < d) return 2;
  if (eq(c1.r - c2.r, d)) return 1;
  return 0;
}
Real distance(const Point &a, const Point &b) { return abs(a - b); }
Real distance(const Line &l, const Point &p) {
  return abs(p - projection(l, p));
}
Real distance(const Line &l, const Line &m) {
  return intersect(l, m) ? 0 : distance(l, m.a);
}
Real distance(const Segment &s, const Point &p) {
  Point r = projection(s, p);
  if (intersect(s, r)) return abs(r - p);
  return min(abs(s.a - p), abs(s.b - p));
}
Real distance(const Segment &a, const Segment &b) {
  if (intersect(a, b)) return 0;
  return min(
      {distance(a, b.a), distance(a, b.b), distance(b, a.a), distance(b, a.b)});
}
Real distance(const Line &l, const Segment &s) {
  if (intersect(l, s)) return 0;
  return min(distance(l, s.a), distance(l, s.b));
}
Point crosspoint(const Line &l, const Line &m) {
  Real A = cross(l.b - l.a, m.b - m.a);
  Real B = cross(l.b - l.a, l.b - m.a);
  if (eq(abs(A), 0.0) && eq(abs(B), 0.0)) return m.a;
  return m.a + (m.b - m.a) * B / A;
}
Point crosspoint(const Segment &l, const Segment &m) {
  return crosspoint(Line(l), Line(m));
}
pair<Point, Point> crosspoint(const Circle &c, const Line l) {
  Point pr = projection(l, c.p);
  Point e = (l.b - l.a) / abs(l.b - l.a);
  if (eq(distance(l, c.p), c.r)) return {pr, pr};
  double base = sqrt(c.r * c.r - norm(pr - c.p));
  return {pr - e * base, pr + e * base};
}
pair<Point, Point> crosspoint(const Circle &c, const Segment &l) {
  Line aa = Line(l.a, l.b);
  if (intersect(c, l) == 2) return crosspoint(c, aa);
  auto ret = crosspoint(c, aa);
  if (dot(l.a - ret.first, l.b - ret.first) < 0)
    ret.second = ret.first;
  else
    ret.first = ret.second;
  return ret;
}
pair<Point, Point> crosspoint(const Circle &c1, const Circle &c2) {
  Real d = abs(c1.p - c2.p);
  Real a = acos((c1.r * c1.r + d * d - c2.r * c2.r) / (2 * c1.r * d));
  Real t = atan2(c2.p.imag() - c1.p.imag(), c2.p.real() - c1.p.real());
  Point p1 = c1.p + Point(cos(t + a) * c1.r, sin(t + a) * c1.r);
  Point p2 = c1.p + Point(cos(t - a) * c1.r, sin(t - a) * c1.r);
  return {p1, p2};
}
pair<Point, Point> tangent(const Circle &c1, const Point &p2) {
  return crosspoint(c1, Circle(p2, sqrt(norm(c1.p - p2) - c1.r * c1.r)));
}
Lines tangent(Circle c1, Circle c2) {
  Lines ret;
  if (c1.r < c2.r) swap(c1, c2);
  Real g = norm(c1.p - c2.p);
  if (eq(g, 0)) return ret;
  Point u = (c2.p - c1.p) / sqrt(g);
  Point v = rotate(PI * 0.5, u);
  for (int s : {-1, 1}) {
    Real h = (c1.r + s * c2.r) / sqrt(g);
    if (eq(1 - h * h, 0)) {
      ret.emplace_back(c1.p + u * c1.r, c1.p + (u + v) * c1.r);
    } else if (1 - h * h > 0) {
      Point uu = u * h, vv = v * sqrt(1 - h * h);
      ret.emplace_back(c1.p + (uu + vv) * c1.r, c2.p - (uu + vv) * c2.r * s);
      ret.emplace_back(c1.p + (uu - vv) * c1.r, c2.p - (uu - vv) * c2.r * s);
    }
  }
  return ret;
}
bool is_convex(const Polygon &p) {
  int n = (int)p.size();
  for (int i = 0; i < n; i++) {
    if (ccw(p[(i + n - 1) % n], p[i], p[(i + 1) % n]) == -1) return false;
  }
  return true;
}
Polygon convex_hull(Polygon &p) {
  int n = (int)p.size(), k = 0;
  if (n <= 2) return p;
  sort(p.begin(), p.end());
  vector<Point> ch(2 * n);
  for (int i = 0; i < n; ch[k++] = p[i++]) {
    while (k >= 2 && cross(ch[k - 1] - ch[k - 2], p[i] - ch[k - 1]) < EPS) --k;
  }
  for (int i = n - 2, t = k + 1; i >= 0; ch[k++] = p[i--]) {
    while (k >= t && cross(ch[k - 1] - ch[k - 2], p[i] - ch[k - 1]) < EPS) --k;
  }
  ch.resize(k - 1);
  return ch;
}
int main() {
  int n;
  IN(n);
  double mi = 1e16, ma = 0;
  Point p;
  cin >> p;
  Polygon P(n);
  for (long long i = 0; i < n; ++i) {
    cin >> P[i];
  }
  double pi = acos(-1);
  for (long long i = 0; i < n; ++i)
    chmin(mi, distance(p, P[i])), chmax(ma, distance(p, P[i]));
  for (long long i = 0; i < n; ++i)
    chmin(mi, distance(Segment(P[i], P[(i + 1) % n]), p)),
        chmax(ma, distance(Segment(P[i], P[(i + 1) % n]), p));
  cout << pi * (ma * ma - mi * mi) << '\n';
}
