def split_closest_values(numbers):
    """  Shrink closes numbers in a list to max\min separated by the dash ('-')
    split_by_range(list_of_int) -> list of integers, separated by str

    Example:
        split_by_range([1, 2, 3, 5, 6, 9]) -> ['1-3', '5-6', '9']

    :param numbers: numbers to shrink to
    :type numbers: list[int]
    :return: list of integers as a string, closest ones are separated by the dash ('-'). In asc. sorted order
    :rtype: list[str]
    """

    if not numbers:
        return []

    result = []
    tmp_last_end_numbers = []

    try:
        numbers = sorted(int(numb) for numb in numbers)
    except ValueError as e:
        logging.exception(e)
        return []

    # first number must be in result
    last_number = numbers.pop(0)
    tmp_last_end_numbers.append(last_number)

    split_flag = False
    for number in numbers:
        if number == last_number:
            continue
        # when following number found -> place flag and continue sequence
        elif number - last_number == 1:
            if not split_flag:
                split_flag = True
        else:
            # new number is out of following sequence range
            if split_flag:
                tmp_last_end_numbers.append(last_number)
                split_flag = False
                result.append('-'.join([str(x) for x in tmp_last_end_numbers]))
            else:
                result.append(str(last_number))

            # release sequence, and start new buffer with the "breaking" number
            tmp_last_end_numbers = []
            tmp_last_end_numbers.append(number)

        # keep in memory prev. number to compare
        last_number = number

    # solving problem of a very last number
    # last number must be in result either
    if split_flag:
        tmp_last_end_numbers.append(last_number)
        result.append('-'.join([str(x) for x in tmp_last_end_numbers]))
    else:
        result.append(str(last_number))

    return result