#include <bits/stdc++.h>
#define FOR(i,a,b) for (i=(a);i<(b);i++)
#define FORR(i,a,b) for (int i=(a);i>=(b);i--)
#define pb push_back
#define pcnt __builtin_popcount
#define show(x) cout<<#x<<" = "<<x<<endl;
#define maxs(x,y) x = max(x,y)
#define mins(x,y) x = min(x,y)
#define fi first
#define se second
#define rng(a) a.begin(),a.end()
#define each(it,c) for(__typeof((c).begin()) it=(c).begin();it!=(c).end();it++)
#define sz(x) (int)(x).size()
#define mp make_pair

using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<pii> vpii;
typedef set<int> si;
typedef pair<ll,ll> pll;
typedef vector<ll> vl;
typedef vector<vl> vvl;
typedef vector<pll> vpll;
typedef set<ll> sl;
ll gcd(ll a,ll b){if(a>b)swap(a,b);for(;a>0;b%=a,swap(a,b));return b;}
int modpow(ll a,ll n,int m){if(a==0)return a;ll p=1;for(;n>0;n/=2,a=a*a%m)if(n&1)p=p*a%m;return(int)p;}
void dout(double d){printf("%.15f\n",d);}

const int iinf = 1e9;
const ll linf = 1e18;
const int mod = 1e9+7;
const double pi = acos(-1);
const double eps = 1e-10;
int n, i, j, k, l;
double x[300][3], p[3], t[3], z[3];
main(){
  cin.tie(0);
  ios::sync_with_stdio(false);
  cin >> n;
  FOR(i, 0, 3)cin >> p[i];
  FOR(i, 0, n){
    FOR(j, 0, 3)cin >> x[i][j];
    FOR(j, 0, 3)x[i][j] -= p[j];
  }
  double ans = 0.;
  FOR(i, 0, n-2)FOR(j, i+1, n-1)FOR(k, j+1, n){
    FOR(l, 0, 3)t[l] = x[i][l] - x[j][l];
    FOR(l, 0, 3)p[l] = x[i][l] - x[k][l];
    FOR(l, 0, 3)z[l] = p[(l+1)%3]*t[(l+2)%3] - p[(l+2)%3]*t[(l+1)%3];
    ans += abs(x[i][0]*z[0]+x[i][1]*z[1]+x[i][2]*z[2]) / sqrt(z[0]*z[0]+z[1]*z[1]+z[2]*z[2]);
  }
  dout(ans);
  return 0;
}