class Solution:
def shortestPalindrome(self, s: 'str') -> 'str':
s = ' '.join(s)
mid = len(s) // 2
while True:
s1 = s[:mid]
if s1[::-1] == s[mid + 1:mid + len(s1) + 1]:
break
mid -= 1
left = s[mid:]
return (left[::-1][:-1] + left).replace(' ', '')