import re


def check_symbols(line, idx_start, idx_end, previous, next):
    pattern = re.compile(r'[^a-zA-Z0-9.]')
    end_next_idx = idx_end + 2
    start_prev_idx = idx_start - 1
    if idx_end != len(line):
        end_next_idx = -1
    if idx_start == 0:
        start_prev_idx = 0
    if next:
        check_next = pattern.findall(next[start_prev_idx: end_next_idx])
    else:
        check_next = []
    if previous:
        check_previous = pattern.findall(previous[start_prev_idx: end_next_idx])
    else:
        check_previous = []
    check_left = pattern.findall(line[start_prev_idx])
    check_right = pattern.findall(line[end_next_idx])

    if check_next or check_previous or check_left or check_right:
        return True
    return False


def get_digit(line):
    digit_pattern = re.compile(r'\d+')
    matches = digit_pattern.finditer(line)
    digits = []
    for match in matches:
        start = match.start()
        end = match.end() - 1
        digit = match.group()
        digits.append({'digit': digit, 'start_idx': start, 'end_idx': end})
    return digits


def play(filename):
    with open(filename) as file:

        total = 0
        lines = file.read().splitlines()

        for i in range(len(lines)):
            current_line = lines[i]

            if i == 0:
                line_previous = ''
            else:
                line_previous = lines[i - 1]

            if i == len(lines) - 1:
                line_next = ''
            else:
                line_next = lines[i + 1]

            digits = get_digit(current_line)
            if digits:
                for digit in digits:
                    is_engine = check_symbols(current_line,
                                              digit['start_idx'],
                                              digit['end_idx'],
                                              line_previous,
                                              line_next)
                    if is_engine:
                        total += int(digit['digit'])

        return total