def xorSequence(l, r):
    if l == 0:
        n = r % 8
        if n == 0 or n == 1:
            return r
        elif n == 2 or n == 3:
            return 2
        elif n == 4 or n == 5:
            return r + 2
        return 0
    return xorSequence(0, r) ^ xorSequence(0, l - 1)