#include <bits/stdc++.h>
using namespace std;

#define _p(...) (void)printf(__VA_ARGS__)
#define forr(x,arr) for(auto&& x:arr)
#define _overload3(_1,_2,_3,name,...) name
#define _rep2(i,n) _rep3(i,0,n)
#define _rep3(i,a,b) for(int i=int(a);i<int(b);++i)
#define rep(...) _overload3(__VA_ARGS__,_rep3,_rep2,)(__VA_ARGS__)
#define _rrep2(i,n) _rrep3(i,0,n)
#define _rrep3(i,a,b) for(int i=int(b)-1;i>=int(a);i--)
#define rrep(...) _overload3(__VA_ARGS__,_rrep3,_rrep2,)(__VA_ARGS__)
#define ALL(x) (x).begin(), (x).end()
#define BIT(n) (1LL<<(n))
#define SZ(x) ((int)(x).size())
#define fst first
#define snd second
typedef long long ll;
typedef vector<int> vi;typedef vector<vi> vvi;typedef pair<int,int> pii;typedef vector<pii> vpii;

void Main() {
  int N;
  cin >> N;
  double px, py, pz;
  cin >> px >> py >> pz;

  vector<double> X(N), Y(N), Z(N);
  rep(i, N) {
    cin >> X[i] >> Y[i] >> Z[i];
  }

  double ans = 0;

  rep(i, N) {
    double ax = X[i];
    double ay = Y[i];
    double az = Z[i];
    rep(j, i+1, N) {
      double bx = X[j];
      double by = Y[j];
      double bz = Z[j];

      double abx = ax - bx;
      double aby = ay - by;
      double abz = az - bz;

      rep(k, j+1, N) {
        double cx = X[k];
        double cy = Y[k];
        double cz = Z[k];

        double acx = ax - cx;
        double acy = ay - cy;
        double acz = az - cz;

        double hx = aby * acz - abz * acy;
        double hy = abz * acx - abx * acz;
        double hz = abx * acy - aby * acx;

        double d = hx * -ax + hy * -ay + hz * -az;

        double si = fabs(hx * px + hy * py + hz * pz + d);
        double bo = sqrt(hx*hx + hy*hy + hz*hz);

        double D = si / bo;
        ans += D;
      }
    }
  }
  _p("%.20f\n", ans);
}
int main() { cin.tie(0); ios::sync_with_stdio(false); Main(); return 0; }