from typing import Sequence
from typing import Tuple


def cross(a: Sequence[int], b: Sequence[int]) -> Tuple[int, int, int]:
    """ Returns the cross product of the three-dimensional vectors a and b """
    ax, ay, az = a
    bx, by, bz = b
    return ay * bz - az * by, az * bx - ax * bz, ax * by - ay * bx