N = int(input())
px, py, pz = map(float, input().split())
X, Y, Z = [0] * N, [0] * N, [0] * N
for i in range(N):
    X[i], Y[i], Z[i] = map(float, input().split())


def plane(i, j, k):
    abx = X[j] - X[i]
    aby = Y[j] - Y[i]
    abz = Z[j] - Z[i]
    acx = X[k] - X[i]
    acy = Y[k] - Y[i]
    acz = Z[k] - Z[i]
    a = aby * acz - abz * acy
    b = abz * acx - abx * acz
    c = abx * acy - aby * acx
    d = -a * X[i] - b * Y[i] - c * Z[i]
    return a, b, c, d


def solve(a, b, c, d, x, y, z):
    return abs(a * x + b * y + c * z + d)/(a ** 2 + b ** 2 + c ** 2)**0.5


ans = 0
for i in range(N):
    for j in range(i + 1, N):
        for k in range(j + 1, N):
            a, b, c, d = plane(i, j, k)
            ans += solve(a, b, c, d, px, py, pz)

print(ans)