class Solution:
    def isValid(self, s: str) -> bool:
        ilist = []
        l = -1
        for char in s:
            if char == "(" or char == "[" or char == "{":
                ilist.append(char)
                l += 1
            elif l < 0:
                return False
            elif char == ")":
                if ilist[l] == "(":
                    del ilist[l]
                    l -= 1
                else:
                    return False
            elif char == "]":
                if ilist[l] == "[":
                    del ilist[l]
                    l -= 1
                else:
                    return False
            elif char == "}":
                if ilist[l] == "{":
                    del ilist[l]
                    l -= 1
                else:
                    return False
        return True if l < 0 else False