#include <bits/stdc++.h>

using namespace std;

long double x[301], y[301], z[301];
long double px,py,pz;
int n;

int main() 
{
    cin.tie(0);
    ios::sync_with_stdio(false); 
    
    cin >> n;
    cin >> px >> py >> pz;
    for (int i = 1; i <= n; i++)
    {
        cin >> x[i] >> y[i] >> z[i];
    }

    long double res = 0;

    for (int i = 1; i <= n; i++)
    {
        for (int j = i + 1; j <= n; j++)
        {
            for (int k = j + 1; k <= n; k++)
            {
                long double a[3], b[3];
                a[0] = x[j] - x[i];
                a[1] = y[j] - y[i];
                a[2] = z[j] - z[i];
                b[0] = x[k] - x[i];
                b[1] = y[k] - y[i];
                b[2] = z[k] - z[i];
                long double A = (a[1] * b[2] - a[2] * b[1]);
                long double B = -(a[0] * b[2] - a[2] * b[0]);
                long double C = (a[0] * b[1] - a[1] * b[0]);
                long double D = (A * x[i] + B * y[i] + C * z[i]);
                long double dist = abs(A * px + B * py + C * pz - D);
                dist /= sqrt(A * A + B * B + C * C);
                res += dist;
            }
        }
    }

    
    cout << fixed;
    cout.precision(18);

    cout << res << '\n';

    return 0;
}