def count_inversion(seq):
    i = 1
    s = 0

    while i < len(seq):
        j = i - 1
        while seq[i] < seq[j]:
            s += 1
            i += 1
            if i == len(seq):
                return s
        i += 1

    return s


def test():
    seq_0 = (1, 2, 5, 3, 4, 7, 6)
    seq_1 = (0, 1, 2, 3, 4)
    seq_2 = list(reversed(range(10)))
    assert count_inversion(seq_0) == 3
    assert count_inversion(seq_1) == 0
    assert count_inversion(seq_2) == 9
    print('ok')


test()