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

int main() {
    int N;
    double Px, Py, Pz;
    cin >> N >> Px >> Py >> Pz;
    struct Point {
        double x, y, z;
    };
    vector<Point> V(N);
    for (int i = 0; i < N; i++) {
        double x, y, z;
        cin >> x >> y >> z;
        x -= Px;
        y -= Py;
        z -= Pz;
        V[i] = {x, y, z};
    }

    auto d = [](const Point A, const Point B) {
        return sqrt(pow(A.x - B.x, 2) + pow(A.y - B.y, 2) + pow(A.z - B.z, 2));
    };


    auto solve = [&](int i, int j, int k) {
        auto &A = V[i], &B = V[j], &C = V[k];
        double s = (d(A, B) + d(B, C) + d(C, A)) / 2;
        double area = sqrt(s * (s - d(A, B)) * (s - d(B, C)) * (s - d(C, A)));
        double vol = A.x * B.y * C.z + A.y * B.z * C.x + A.z * B.x * C.y
                     - A.z * B.y * C.x - A.y * B.x * C.z - A.x * B.z * C.y;
        vol /= 2;
        return abs(vol / area);
    };

    double ans = 0;
    for (int i = 0; i < N; i++) {
        for (int j = i + 1; j < N; j++) {
            for (int k = j + 1; k < N; k++) {
                ans += solve(i, j, k);
            }
        }
    }

    cout << fixed << setprecision(10) << ans << endl;
}