import sys

sys.setrecursionlimit(10 ** 6)
from bisect import *
from collections import *
from heapq import *

int1 = lambda x: int(x) - 1
p2D = lambda x: print(*x, sep="\n")
def II(): return int(sys.stdin.readline())
def MI(): return map(int, sys.stdin.readline().split())
def MI1(): return map(int1, sys.stdin.readline().split())
def MF(): return map(float, sys.stdin.readline().split())
def LI(): return list(map(int, sys.stdin.readline().split()))
def LI1(): return list(map(int1, sys.stdin.readline().split()))
def LF(): return list(map(float, sys.stdin.readline().split()))
def LLI(rows_number): return [LI() for _ in range(rows_number)]
dij = [(0, 1), (1, 0), (0, -1), (-1, 0)]

def main():
    # 3点Q1,Q2,Q3からできる三角形を底面とし、Pを頂点とする三角すいを考える
    # 底面積(△Q1Q2Q3)と体積が分かれば高さ(点Pと平面Q1Q2Q3の距離)が分かる
    n = II()
    xp, yp, zp = LF()
    qq = [LF() for _ in range(n)]
    qq = [[x - xp, y - yp, z - zp] for x, y, z in qq]
    ans = 0
    for k, (x3, y3, z3) in enumerate(qq):
        for j, (x2, y2, z2) in enumerate(qq[:k]):
            for (x1, y1, z1) in qq[:j]:
                # 体積(の6倍)vを求める
                v = abs(x1 * y2 * z3 + y1 * z2 * x3 + z1 * x2 * y3 - z1 * y2 * x3 - y1 * x2 * z3 - x1 * z2 * y3)
                # 底面積(の2倍)sを求める
                xa, ya, za = x2 - x1, y2 - y1, z2 - z1
                xb, yb, zb = x3 - x1, y3 - y1, z3 - z1
                s = ((xa*yb-ya*xb)**2+(ya*zb-za*yb)**2+(za*xb-xa*zb)**2)**0.5
                # h=v/sより高さhを求める
                ans += v / s
    print(ans)

main()