#include <iostream>
#include <vector>
#include <cmath>
#include <map>
#include <set>
#include <iomanip>
#include <queue>
#include <algorithm>
#include <numeric>
#include <deque>
#include <complex>

using namespace std;

using ld = long double;

vector<ld> x, y, z;

ld dist(int i, int j, int k){
    ld dx1, dx2, dy1, dy2, dz1, dz2, a, b, c, d;
    dx1 = x[j]-x[i];
    dy1 = y[j]-y[i];
    dz1 = z[j]-z[i];
    dx2 = x[k]-x[i];
    dy2 = y[k]-y[i];
    dz2 = z[k]-z[i];
    a = dy1*dz2 - dz1*dy2;
    b = dz1*dx2 - dx1*dz2;
    c = dx1*dy2 - dy1*dx2;
    d = a * x[i] + b * y[i] + c * z[i];
    return abs(d)/sqrt(a*a+b*b+c*c);
}

int main(){

    int N;
    cin >> N;
    x.resize(N); y.resize(N), z.resize(N);
    ld px, py, pz, xx, yy, zz, ans=0;
    cin >> px >> py >> pz;
    for (int i=0; i<N; i++){
        cin >> xx >> yy >> zz;
        x[i] = xx-px;
        y[i] = yy-py;
        z[i] = zz-pz;
    }

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

    cout << setprecision(18) << ans << endl;

    return 0;
}