def test2():
    assert digit_at_index(13) == 1
    assert digit_at_index2(13) == 1
def test12():
    assert digit_at_index(-10) == -1
    assert digit_at_index2(-10) == -1
def test11():
    assert digit_at_index(-1) == -1
    assert digit_at_index2(-1) == -1
def test10():
    assert digit_at_index(0) == 0
    assert digit_at_index2(0) == 0
def test1():
    assert digit_at_index(5) == 5
    assert digit_at_index2(5) == 5
def test3():
    assert digit_at_index(19) == 4
    assert digit_at_index2(19) == 4