#include <iostream>
#include <vector>
#include <algorithm>
#include <iomanip>
using namespace std;

#define RREP(i,s,e) for (i = s; i >= e; i--)
#define rrep(i,n) RREP(i,(int)(n)-1,0)
#define REP(i,s,e) for (i = s; i <= e; i++)
#define rep(i,n) REP(i,0,(int)(n)-1)
#define INF 100000000

typedef long long ll;

double det(double* p, double* q, double* r) {
    int i;
    double ret = 0;
    rep (i,3) ret += p[i]*q[(i+1)%3]*r[(i+2)%3];
    rep (i,3) ret -= p[i]*q[(i+2)%3]*r[(i+1)%3];
    return ret;
}

double calc_area(double* p, double* q) {
    int i;
    double ret = 0;
    ret += (p[1]*q[2]-p[2]*q[1]) * (p[1]*q[2]-p[2]*q[1]);
    ret += (p[2]*q[0]-p[0]*q[2]) * (p[2]*q[0]-p[0]*q[2]);
    ret += (p[0]*q[1]-p[1]*q[0]) * (p[0]*q[1]-p[1]*q[0]);
    return sqrt(ret);
}

int main() {
    int i, j, k, l, n;
    double p[3], a[3], b[3];
    double xyz[300][3];
    double ans = 0;
    cin >> n;
    rep (i,3) cin >> p[i];
    rep (i,n) {
        cin >> xyz[i][0] >> xyz[i][1] >> xyz[i][2];
        rep (j,3) xyz[i][j] -= p[j];
    }
    rep (i,n) REP (j,i+1,n-1) REP (k,j+1,n-1) {
        double vol = abs(det(xyz[i],xyz[j],xyz[k])/6);
        rep (l,3) a[l] = xyz[j][l] - xyz[i][l];
        rep (l,3) b[l] = xyz[k][l] - xyz[i][l];
        double area = calc_area(a,b) / 2;
        ans += vol * 3 / area;
    }
    cout << fixed << setprecision(10) << ans << endl;
    return 0;
}