#include <iostream>
#include <string>
#include <vector>
#include <cmath>
#include <algorithm>
#include <cstdlib>
#include <ctime>
#include <cstdio>
#include <functional>
#include <set>
#include <sstream>
#include <map>
#include <queue>

using namespace std;
 
const double eps=1e-10;

vector<double> X,Y,Z;
double px,py,pz;


double dist(int i,int j,int k)
{
	double vijx,vijy,vijz;
	double vikx,viky,vikz;

	vijx=X[j]-X[i];
	vijy=Y[j]-Y[i];
	vijz=Z[j]-Z[i];

	vikx=X[k]-X[i];
	viky=Y[k]-Y[i];
	vikz=Z[k]-Z[i];

	//a(x-X[i])+b(y-Y[i])+c(z-Z[i])=0
	//ax+by+cz+(-aX[i]-bY[i]-cZ[i])=0

	double a=vijy*vikz - vijz*viky;
	double b=vijz*vikx - vijx*vikz;
	double c=vijx*viky - vijy*vikx;
	double d=-a*X[i]-b*Y[i]-c*Z[i];

	double res=abs(a*px+b*py+c*pz+d)/sqrt(a*a+b*b+c*c);

	return res;

}

int main()
{

	int n;
	cin>>n;

	cin>>px>>py>>pz;

	double res=0.0;

	X.resize(n);
	Y.resize(n);
	Z.resize(n);
	for(int i=0;i<n;i++){
		cin>>X[i]>>Y[i]>>Z[i];
	}

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

	printf("%.12f\n",res);

	return 0;
}