def mul4(a, bs):
    if (a == 0):
        return 0
    r = 0
    for b in bs:
        r <<= 8
        if (b != 0):
            r = (r | mul(a, b))
    return r
def mul4(a, bs):
    if (a == 0):
        return 0
    r = 0
    for b in bs:
        r <<= 8
        if (b != 0):
            r = (r | mul(a, b))
    return r