func_code_string: #include <bits/stdc++.h>   using namespace std;   template <class T>   inline void Read(T &x) {     int f = 1;     char t = getchar();     while (t <  0  || t >  9 ) {       if (t ==  - ) f = -1;       t = getchar();     }     x = 0;     while (t >=  0  && t <=  9 ) {       x = x * 10 + t -  0 ;       t = getchar();     }     x *= f;   }   template <class T>   inline void chkmin(T &x, T y) {     if (x > y) x = y;   }   template <class T>   inline void chkmax(T &x, T y) {     if (x < y) x = y;   }   const int maxn = 200005;   const double inf = 2e18;   const double pi = acos(-1.0);   struct point {     long double x, y;     point() {}     point(long double x, long double y) : x(x), y(y) {}     void read() { cin >> x >> 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, long double v) {     return point(a.x * v, a.y * v);   }   point operator/(const point &a, long double v) {     return point(a.x / v, a.y / v);   }   long double operator^(const point &a, const point &b) {     return a.x * b.y - a.y * b.x;   }   int n;   point P, g[maxn];   long double dis(point &a, point &b) {     return (a.x - b.x) * (a.x - b.x) + (a.y - b.y) * (a.y - b.y);   }   long double maxr = -inf, minr = inf;   void calc(point &a, point &b) {     long double A = dis(a, P), B = dis(b, P), C = dis(a, b);     long double area = (a - P) ^ (b - P);     long double Height = area * area / C;     if (A < B) swap(A, B);     if (A > B + C) return;     chkmax(maxr, Height);     chkmin(minr, Height);   }   void input() {     Read(n);     P.read();     for (register int i = 1; i <= n; i++) g[i].read();     g[0] = g[n];     for (register int i = 1; i <= n; i++) calc(g[i], g[i - 1]);   }   void solve() {     for (register int i = 1; i <= n; i++) {       chkmax(maxr, dis(g[i], P));       chkmin(minr, dis(g[i], P));     }     printf( %.18lf n , (double)(maxr - minr) * pi);   }   int main() {     input();     solve();     return 0;   }   