🐍🧩 Задача о поврежденной XML-строке

        string = input()
temp = string
tags = (string.replace('<', ' ').replace('>', ' ')).split()
 
def checkTags(xml):
    stack = []
    open_right = None
    tags = (xml.replace('<', ' ').replace('>', ' ')).split()
    for i in tags:
        if i.isalpha():
            stack.append(i)
        elif i.startswith('/') and i[1:] in stack:
            stack.remove(i[1:])
        else:
             open_right = i
             return open_right
    if len(stack) == 0 and open_right == None:
        return 'closed'
    else:
        return stack
 
 
if checkTags(temp) != 'closed':
    exchange = [i for e in checkTags(temp) for i in e]
    exchange.extend(['<', '>', '/'])
    temp = list(string)
    answers = []
    for j in range(len(temp)):
        for i in '<>/qwertyuiopasdfghjklzxcvbnm':
            if temp[j] in set(exchange):
                temp[j] = i
                xml = ''.join(temp)
                if checkTags(xml) == 'closed':
                    tags = (xml.replace('<', ' ').replace('>', ' ')).split()
                    result = (''.join(["<" + i + ">" for i in tags]))
                    if len(result) == len(string):
                        answers.append(result)
                else:
                    temp = list(string)
 
    print(max(answers))      
else:
    print(''.join(["<" + i + ">" for i in tags]))
    

        def checkTags(xml):
    if xml[0] != '<' or xml[-1] != '>':
        return 0
    opening_tag = []
    i = 0
    while True:
        if i == len(xml):
            break
        if xml[i] != '<':
            return 0
        i += 1
        closing_tag = 0
        if xml[i] == '/':
            closing_tag  = 1
            i += 1
        if not ('a' <= xml[i] and xml[i] <= 'z'):
            return 0
        tag = xml[i]
        i += 1
        while 'a' <= xml[i] and xml[i] <= 'z':
            tag += xml[i]
            i += 1
        if xml[i] != '>':
            return 0
        i += 1
        if closing_tag  == 0:
            opening_tag.append(tag)
        else:
            if len(opening_tag) == 0:
                return 0
            if opening_tag[-1] != tag:
                return 0
            del opening_tag[-1]
    return len(opening_tag) == 0
def changeSymbol():
    for i in range(len(string)):
        temp = string.copy()
        temp[i] = j
        if checkTags(temp):
            result.append(temp)
string = list(input())
opened_chevron = string.count('<')
closed_chevron = string.count('>')
slashes = string.count('/')
letters = {}
result = []
for i in string:
    letters[i] = letters.get(i, 0) + 1
for j in '<>/qwertyuiopasdfghjklzxcvbnm':
    if j == '<' and opened_chevron % 2:
        changeSymbol()
                
    elif j == '>' and closed_chevron % 2:
        changeSymbol()
                
    elif j == '/' and closed_chevron // 2 != slashes:
        changeSymbol()
                
    elif j in letters and letters[j] % 2:
        changeSymbol()
            
for i in result:
    print(''.join(i))