class Solution(object):

    def isValid(self, s):

        """

        :type s: str

        :rtype: bool

        """

        dic = {')':'(', '}':'{', ']':'['}

        res = []

        for i in s:

            if i in dic.keys():

                if res == [] or dic[i] != res[-1]:

                    return False

                res.pop()

            else:

                res.append(i)

        return res == []