#include <bits/stdc++.h>

using namespace std;

struct point {
  double x, y, z;
  point(double x, double y, double z): x(x), y(y), z(z) {}
  point(): x(0), y(0), z(0) {}
};

point operator-(const point &a, const point &b) {
  return point(a.x - b.x, a.y - b.y, a.z - b.z);
}

double dot(const point&a, const point&b) {
  return a.x * b.x + a.y * b.y + a.z * b.z;
}

double norm(const point &a) {
  return sqrt(dot(a, a));
}

point cross(const point &a, const point &b) {
  return point(a.y * b.z - a.z * b.y, a.z * b.x - a.x * b.z, a.x * b.y - a.y * b.x);
}


double dist(point a, point b, point c, point p) {
  p = p - a;
  b = b - a;
  c = c - a;
  a = a - a;
  point n = cross(b, c);
  return abs(dot(p, n) / norm(n));
}

int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  
  int n;
  cin >> n;

  point p;
  vector<point> v(n);
  
  cin >> p.x >> p.y >> p.z;
  for (int i = 0; i < n; i++)
    cin >> v[i].x >> v[i].y >> v[i].z;

  double ret = 0;
  for (int i = 0; i < n; i++) {
    for (int j = i + 1; j < n; j++) {
      for (int k = j + 1; k < n; k++) {
        ret += dist(v[i], v[j], v[k], p);
      }
    }
  }

  cout << fixed << setprecision(12) << ret << endl;
  
  return 0;
}