package q1xx;

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.InputMismatchException;

public class Q147 {
	InputStream is;
	PrintWriter out;
	String INPUT = "";
	
	void solve()
	{
		int n = ni();
		double[] P = new double[]{nd(), nd(), nd()};
		double[][] co = new double[n][];
		for(int i = 0;i < n;i++){
			co[i] = new double[]{nd(), nd(), nd()};
		}
		
		double ret = 0;
		for(int i = 0;i < n;i++){
			for(int j = i+1;j < n;j++){
				for(int k = j+1;k < n;k++){
					double dist = d3d(co[i], co[j], co[k], P);
					ret += dist;
				}
			}
		}
		out.printf("%.13f\n", ret);
	}
	
	// p=ax+by+cz
	
	double d3d(double[] a, double[] b, double[] c, double[] p)
	{
		double[] bma = sub(Arrays.copyOf(b, 3), a);
		double[] cma = sub(Arrays.copyOf(c, 3), a);
		double[] pma = sub(Arrays.copyOf(p, 3), a);
		double[] cbc = cross(bma, cma);
		return Math.abs(dot(pma, cbc)) / Math.sqrt(dot(cbc, cbc));
	}
	
	double[] cross(double[] a, double[] b)
	{
		return new double[]{
				a[1]*b[2]-a[2]*b[1],
				a[2]*b[0]-a[0]*b[2],
				a[0]*b[1]-a[1]*b[0]
		};
	}
	
	double[] mul(double a, double[] b)
	{
		for(int i = 0;i < b.length;i++)b[i] *= a;
		return b;
	}
	
	double dot(double[] a, double[] b)
	{
		double ret = 0;
		for(int i = 0;i < a.length;i++)ret += a[i]*b[i];
		return ret;
	}
	
	double[] sub(double[] a, double[] v)
	{
		for(int i = 0;i < v.length;i++)a[i] -= v[i];
		return a;
	}
	
	void run() throws Exception
	{
		is = INPUT.isEmpty() ? System.in : new ByteArrayInputStream(INPUT.getBytes());
		out = new PrintWriter(System.out);
		
		long s = System.currentTimeMillis();
		solve();
		out.flush();
		if(!INPUT.isEmpty())tr(System.currentTimeMillis()-s+"ms");
	}
	
	public static void main(String[] args) throws Exception { new Q147().run(); }
	
	private byte[] inbuf = new byte[1024];
	private int lenbuf = 0, ptrbuf = 0;
	
	private int readByte()
	{
		if(lenbuf == -1)throw new InputMismatchException();
		if(ptrbuf >= lenbuf){
			ptrbuf = 0;
			try { lenbuf = is.read(inbuf); } catch (IOException e) { throw new InputMismatchException(); }
			if(lenbuf <= 0)return -1;
		}
		return inbuf[ptrbuf++];
	}
	
	private boolean isSpaceChar(int c) { return !(c >= 33 && c <= 126); }
	private int skip() { int b; while((b = readByte()) != -1 && isSpaceChar(b)); return b; }
	
	private double nd() { return Double.parseDouble(ns()); }
	private char nc() { return (char)skip(); }
	
	private String ns()
	{
		int b = skip();
		StringBuilder sb = new StringBuilder();
		while(!(isSpaceChar(b))){ // when nextLine, (isSpaceChar(b) && b != ' ')
			sb.appendCodePoint(b);
			b = readByte();
		}
		return sb.toString();
	}
	
	private char[] ns(int n)
	{
		char[] buf = new char[n];
		int b = skip(), p = 0;
		while(p < n && !(isSpaceChar(b))){
			buf[p++] = (char)b;
			b = readByte();
		}
		return n == p ? buf : Arrays.copyOf(buf, p);
	}
	
	private char[][] nm(int n, int m)
	{
		char[][] map = new char[n][];
		for(int i = 0;i < n;i++)map[i] = ns(m);
		return map;
	}
	
	private int[] na(int n)
	{
		int[] a = new int[n];
		for(int i = 0;i < n;i++)a[i] = ni();
		return a;
	}
	
	private int ni()
	{
		int num = 0, b;
		boolean minus = false;
		while((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'));
		if(b == '-'){
			minus = true;
			b = readByte();
		}
		
		while(true){
			if(b >= '0' && b <= '9'){
				num = num * 10 + (b - '0');
			}else{
				return minus ? -num : num;
			}
			b = readByte();
		}
	}
	
	private long nl()
	{
		long num = 0;
		int b;
		boolean minus = false;
		while((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'));
		if(b == '-'){
			minus = true;
			b = readByte();
		}
		
		while(true){
			if(b >= '0' && b <= '9'){
				num = num * 10 + (b - '0');
			}else{
				return minus ? -num : num;
			}
			b = readByte();
		}
	}
	
	private static void tr(Object... o) { System.out.println(Arrays.deepToString(o)); }
}