def split_pair_occurrence(input_str):
    """
    Q9HD36.A79T (x11) → (Q9HD36.A79T, 11)
    """
    if '(x' not in input_str:
        return input_str, 1

    pair, occurrence = [item.strip() for item in input_str.split()]
    occurrence = int(occurrence[2:-1])

    return pair, occurrence