from collections import *
from itertools import *
from functools import *
from heapq import *
import sys,math
input = sys.stdin.readline

N = int(input())
px,py,pz = map(float,input().split())
X = [tuple(map(float,input().split())) for _ in range(N)]
ans = 0

def plane(A,B,C):
    
    #三次元上の点A,B,Cを通る平面ax+by+cz+d=0を求める
    # return (a,b,c,d)
    
    ax,ay,az = A
    bx,by,bz = B 
    cx,cy,cz = C
    a = (by-ay)*(cz-az) - (cy-ay)*(bz-az)
    b = (bz-az)*(cx-ax) - (cz-az)*(bx-ax)
    c = (bx-ax)*(cy-ay) - (cx-ax)*(by-ay)
    d = -(a*ax+b*ay+c*az)   
    return (a,b,c,d)
    
    
for i in range(N-2):
    xi = X[i]
    for j in range(i+1,N-1):
        xj = X[j] 
        for k in range(j+1,N):
            xk = X[k]
            a,b,c,d = plane(xi,xj,xk)
            ans += abs(a*px+b*py+c*pz+d)/math.sqrt(a**2+b**2+c**2)
print(ans)