/* -*- coding: utf-8 -*-
 *
 * 132.cc: No.132 点と平面との距離 - yukicoder
 */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<functional>
 
using namespace std;

/* constant */

const int MAX_N = 300;

/* typedef */

template <typename T>
struct Pt3d {
  T x, y, z;

  Pt3d() {}
  Pt3d(T _x, T _y, T _z) : x(_x), y(_y), z(_z) {}
  Pt3d(const Pt3d& pt) : x(pt.x), y(pt.y), z(pt.z) {}

  bool operator==(const Pt3d pt) const {
    return x == pt.x && y == pt.y && z == pt.z;
  }
  Pt3d<T> operator+(const Pt3d pt) const {
    return Pt3d<T>(x + pt.x, y + pt.y, z + pt.z);
  }
  Pt3d<T> operator-() const {
    return Pt3d<T>(-x, -y, -z);
  }
  Pt3d<T> operator-(const Pt3d pt) const {
    return Pt3d<T>(x - pt.x, y - pt.y, z - pt.z);
  }
  Pt3d<T> operator*(T t) const {
    return Pt3d<T>(x * t, y * t, z * t);
  }
  Pt3d<T> operator/(T t) const {
    return Pt3d<T>(x / t, y / t, z / t);
  }
  T dot(Pt3d v) const { return x * v.x + y * v.y + z * v.z; }
  Pt3d<T> cross(Pt3d v) const {
    return Pt3d<T>(y * v.z - z * v.y, z * v.x - x * v.z, x * v.y - y * v.x);
  }
  Pt3d<T> mid(const Pt3d pt) {
    return Pt3d<T>((x + pt.x) / 2, (y + pt.y) / 2, (z + pt.z) / 2);
  }
  T d2() { return x * x + y * y + z * z; }
  double d() { return sqrt(d2()); }
};

typedef Pt3d<double> pt3d;

/* global variables */

pt3d p, qs[MAX_N];

/* subroutines */

/* main */

int main() {
  int n;
  cin >> n;

  cin >> p.x >> p.y >> p.z;

  for (int i = 0; i < n; i++)
    cin >> qs[i].x >> qs[i].y >> qs[i].z;

  double sum = 0.0;
  
  for (int i = 0; i < n; i++) {
    pt3d &q0 = qs[i];
    for (int j = i + 1; j < n; j++) {
      pt3d &q1 = qs[j];
      pt3d v1 = q1 - q0;
      for (int k = j + 1; k < n; k++) {
	pt3d &q2 = qs[k];
	pt3d v2 = q2 - q0;
	pt3d nv = v1.cross(v2);
	double d = abs((p - q0).dot(nv)) / nv.d();
	sum += d;
      }
    }
  }

  printf("%.11lf\n", sum);
  return 0;
}