#include <bits/stdc++.h>
using namespace std;
struct pnt {
  long double x, y;
};
long double dst(pnt& a, pnt& b) {
  return sqrtl((a.x - b.x) * (a.x - b.x) + (a.y - b.y) * (a.y - b.y));
}
long long pr(pnt a, pnt b, pnt c) {
  return (b.x - a.x) * (c.y - a.y) - (b.y - a.y) * (c.x - a.x);
}
bool intersec(pnt p1, pnt p2) {
  pnt p3, p4;
  p3.x = 0;
  p3.y = 0;
  p4.x = 1e9 + 7;
  p4.y = 1;
  long double a1 = p1.y - p2.y;
  long double b1 = p2.x - p1.x;
  long double c1 = -(a1 * p1.x + b1 * p1.y);
  long double a2 = p3.y - p4.y;
  long double b2 = p4.x - p3.x;
  long double c2 = 0;
  long double X = (c2 * b1 - b2 * c1) / (a1 * b2 - b1 * a2);
  long double Y = (a2 * c1 - a1 * c2) / (a1 * b2 - a2 * b1);
  if (X >= 0 && (min(p1.x, p2.x) <= X && X <= max(p1.x, p2.x) &&
                 (min(p1.y, p2.y) <= Y && Y <= max(p1.y, p2.y)))) {
    return true;
  }
  return false;
}
long double dst_line(pnt a, long double A, long double B, long double C) {
  return (A * a.x + B * a.y + C) / (sqrtl(A * A + B * B));
}
signed main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  ;
  signed n;
  cin >> n;
  pnt P;
  cin >> P.x >> P.y;
  vector<pnt> A(n);
  for (signed i = 0; i < n; ++i) {
    cin >> A[i].x >> A[i].y;
    A[i].x -= P.x;
    A[i].y -= P.y;
  }
  long double mi = ((long double)1e9 + 7) * 1.0, ma = 0.0;
  P = {(long double)0.0, (long double)0.0};
  signed cnt = 0;
  for (signed i = 0; i < n; ++i) {
    if (intersec(A[i], A[(i + 1) % n])) {
      ++cnt;
    }
    long double D =
        dst_line(P, (A[i].y - A[(i + 1) % n].y), (A[(i + 1) % n].x - A[i].x),
                 (A[i].x * A[(i + 1) % n].y - A[i].y * A[(i + 1) % n].x));
    if (D < 0) {
      D = -D;
    }
    long double mx =
        sqrtl(D * D + dst(A[i], A[(i + 1) % n]) * dst(A[i], A[(i + 1) % n]));
    long double cur_mx = max(dst(P, A[i]), dst(P, A[(i + 1) % n]));
    if (cur_mx > mx) {
      mi = min(mi, min(dst(P, A[i]), dst(P, A[(i + 1) % n])));
    } else {
      mi = min(mi, D);
    }
    ma = max(ma, dst(P, A[i]));
  }
  if (cnt % 2 == 1) {
    mi = 0;
  }
  cout << fixed;
  cout << setprecision(10);
  ;
  cout << (long double)(3.1415926535897) * (ma * ma - mi * mi);
  return 0;
}
