def simplify2(word):
    """
    normalize and simplify a vni word:
    * move tone digit to the end
    * return only digits
    * return 0 if there is no digit
    """
    if word.isalpha():
        return '0'
    ret = ''
    tone = ''
    for letter in word:
        if '1' <= letter <= '9':
            if '1' <= letter <= '5':
                if len(tone) > 0:
                    return '#'
                tone = letter
            else:
                ret += letter
    return ret + tone
