using System;
using System.Collections.Generic;
using System.Linq;

namespace yukicoder
{
	class Vector3{
		public double x,y,z;
		public Vector3(double _x,double _y,double _z){ x=_x;y=_y;z=_z; }
		public Vector3():this(0,0,0){}
		public Vector3(double[] a):this(a[0],a[1],a[2]){}
		public static Vector3 operator-(Vector3 s,Vector3 o) { return new Vector3(s.x-o.x,s.y-o.y,s.z-o.z); }
		public Vector3 cross_product(Vector3 o) { return new Vector3(y*o.z-z*o.y,z*o.x-x*o.z,x*o.y-y*o.x); }
		public double inner_product(Vector3 o) { return x*o.x+y*o.y+z*o.z; }
		public double norm() { return Math.Sqrt(x*x+y*y+z*z); }
		
	}
	class Program
	{
		public static void Main(string[] args)
		{
			int n;
			Vector3 P;
			Vector3[] l;
			double sum;
			n = int.Parse(Console.ReadLine());
			P = new Vector3(Console.ReadLine().Split(' ').Select(x=>double.Parse(x)).ToArray());
			l = new Vector3[300];
			for(int i=0;i<n;i++){
				l[i] = (new Vector3(Console.ReadLine().Split(' ').Select(x=>double.Parse(x)).ToArray()))-P;
			}
			sum=0;
			for(int i=0;i<n;i++)for(int j=i+1;j<n;j++)for(int k=j+1;k<n;k++){
				Vector3 t = (l[j]-l[i]).cross_product(l[k]-l[i]);
				sum += Math.Abs(l[i].inner_product(t))/t.norm();
			}
			Console.WriteLine(sum);
		}
	}
}