import numpy as np
from scipy import linalg
import itertools

N = int(input())
P = np.array(list(map(float, input().split())) + [1])
Q = np.array([list(map(float, input().split())) + [1] for _ in range(N)])

ans = 0
for t in itertools.combinations(range(N), 3):
    ns = linalg.null_space(Q[list(t)])
    ans += abs(float(P @ ns)) / (np.linalg.norm(ns[:-1]))
print(ans)