def m(a, b):
    x1, y1, z1 = a
    x2, y2, z2 = b
    return (x1-x2, y1-y2, z1-z2)


def cross(a, b):
    x1, y1, z1 = a
    x2, y2, z2 = b
    return (y1*z2-z1*y2, z1*x2-x1*z2, x1*y2-y1*x2)


def dot(a, b):
    x1, y1, z1 = a
    x2, y2, z2 = b
    return x1*x2+y1*y2+z1*z2


def tp(a, b, c):
    return dot(a, cross(b, c))


def main():
    N = int(input())
    *P, = map(float, input().split())
    xyz = [tuple(map(float, input().split())) for i in range(N)]
    ans = 0
    for i in range(N):
        for j in range(i):
            for k in range(j):
                vol = tp(m(P, xyz[i]), m(P, xyz[j]), m(P, xyz[k]))
                bv = cross(m(xyz[i], xyz[j]), m(xyz[i], xyz[k]))
                bs = (dot(bv, bv))**0.5
                ans += abs(vol/bs)

    print(f'{ans:.12f}')


if __name__ == '__main__':
    main()