#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;



int main(void)
{
	int n;
	double px, py, pz;
	double x[SIZE], y[SIZE], z[SIZE];
	double res = 0.0;
	double a, b, c, d;

	cin >> n;
	cin >> px >> py >> pz;

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

	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++) {

				a = (y[j] - y[i]) * (z[k] - z[i]) - (y[k] - y[i]) * (z[j] - z[i]);
				b = (z[j] - z[i]) * (x[k] - x[i]) - (z[k] - z[i]) * (x[j] - x[i]);
				c = (x[j] - x[i]) * (y[k] - y[i]) - (x[k] - x[i]) * (y[j] - y[i]);
				d =  - a * x[i] - b * y[i] - c * z[i];

				res += fabs(a * px + b * py + c * pz + d) / sqrt(a * a + b * b + c * c);
			}
		}
	}
	cout << fixed << setprecision(10) << res << endl;

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

	}*/