class Solution:
def isValid(self , s: str) -> bool:
if not s: return False
if len(s)%2!=0: return False
match,mark={')':'(',']':'[','}':'{'},[]
for item in s:
if item in ['(','[','{']:
mark.append(item)
elif item in [')',']','}']:
if not mark: return False
if mark[-1]==match[item]:
mark.pop()
else: return False
return not mark