#include "bits/stdc++.h"
#define ALL(obj) (obj).begin(),(obj).end()
#define RALL(obj) (obj).rbegin(),(obj).rend()
#define REP(i, n) for(int i = 0; i < (int)(n); i++)
#define REPR(i, n) for(int i = (int)(n); i >= 0; i--)
#define FOR(i,n,m) for(int i = (int)(n); i < int(m); i++)
using namespace std;
typedef long long ll;
const int MOD = 1e9 + 7;
const int INF = MOD - 1;
const ll LLINF = 4e18;

double dist(double p[], double a[], double b[], double c[]) {
    double A = (b[1] - a[1])*(c[2] - a[2]) - (c[1] - a[1])*(b[2] - a[2]); 
    double B = (b[2] - a[2])*(c[0] - a[0]) - (c[2] - a[2])*(b[0] - a[0]); 
    double C = (b[0] - a[0])*(c[1] - a[1]) - (c[0] - a[0])*(b[1] - a[1]);
    double D = -(A*a[0] + B * a[1] + C * a[2]);
    return abs(A*p[0] + B * p[1] + C * p[2] + D) / sqrt(A*A + B * B + C * C);
}

int main() {
    int n; cin >> n;
    double p[3];
    cin >> p[0] >> p[1] >> p[2];
    double v[300][3];
    REP(i, n) {
        cin >> v[i][0] >> v[i][1] >> v[i][2];
    }
    double ans = 0;
    REP(i, n - 2) {
        FOR(j, i + 1, n - 1) {
            FOR(k, j + 1, n) {
                ans += dist(p, v[i], v[j], v[k]);
            }
        }
    }
    printf("%.10f", ans);
    getchar(); getchar();
}