第十二届蓝桥杯Python程序设计赛B组J题

第十二届蓝桥杯Python程序设计赛B组J题 MOD = 1000000007
s = input()
level = {s}  #set型 def isValid(string):
    count = 0
    for si in string:
        for i in range(len(si)):
            if si[i] == '(':
                count += 1
            elif si[i] == ')':
                count -= 1
            if count < 0:
                return
    return count def b(seting):
    y = 0
    for x in seting:
        if isValid(x) == 0:
            y = y + 1
    return y a = isValid(level)
print(a) if a > 0:
    next_level = set()
    while a > 0:
        for item in level:
            for i in range(len(item) + 1):
                next_level.add(item[:i] + ")" + item[i:])
        level.symmetric_difference_update(next_level)    #  用next_level更新level
        a -= 1
    print(b(next_level))
elif a < 0:
    next_level = set()
    while a < 0:
        for item in level:
            for i in range(len(item) + 1):
                next_level.add(item[:i] + "(" + item[i:])
        level.symmetric_difference_update(next_level) # 用next_level更新level
        a = a + 1
    print(b(next_level))

测试系统提交显示错误，希望有大佬帮忙看看哪里有问题。