#define _CRT_SECURE_NO_WARNINGS
#define _USE_MATH_DEFINES
#include <iostream>
#include <map>
#include <list>
#include <cstdio>
#include <cmath>
#include <cstring>
#include <string>
#include <vector>
#include <algorithm>
#include <utility>
#include <queue>
#include <iomanip>
#define INF 1050000000
#define SIZE 300
#define MOD 1000000007

using namespace std;


/* 平面と点との距離 */
double distance(vector<double> P, vector<double> Q1, vector<double> Q2, vector<double> Q3)
{
	double res = 0.0;
	double a, b, c, d;

				a = (Q2[1] - Q1[1]) * (Q3[2] - Q1[2]) - (Q3[1] - Q1[1]) * (Q2[2] - Q1[2]);
				b = (Q2[2] - Q1[2]) * (Q3[0] - Q1[0]) - (Q3[2] - Q1[2]) * (Q2[0] - Q1[0]);
				c = (Q2[0] - Q1[0]) * (Q3[1] - Q1[1]) - (Q3[0] - Q1[0]) * (Q2[1] - Q1[1]);
				d =  - a * Q1[0] - b * Q1[1] - c * Q1[2];

				res += fabs(a * P[0] + b * P[1] + c * P[2] + d) / sqrt(a * a + b * b + c * c);
	
	return (res);
}

int main(void)
{
	int n;
	vector<double> P;
	double x, y, z;
	vector<double> Q[SIZE];
	double res = 0.0;

	cin >> n;
	cin >> x >> y >> z;
	P.push_back(x);
	P.push_back(y);
	P.push_back(z);

	for (int i = 0; i < n; i++) {
		cin >> x >> y >> z;
			Q[i].push_back(x);
			Q[i].push_back(y);
			Q[i].push_back(z);
	}

	for (int i = 0; i < n - 2; i++) {
		for (int j = i + 1; j < n - 1; j++) {
			for (int k = j + 1; k < n; k++) {
				res += distance(P, Q[i], Q[j], Q[k]);
			}
		}
	}
	cout << fixed << setprecision(10) << res << endl;

	return (0);
}
/*for (int i = 0; i < n; i++) {

	}*/