另辟蹊径
while 1: try: str = input().strip() max = 0 n = len(str) if n == 0: print(0) else: for i in range(n-1): if str[i] == str[i+1]: for a in range(n-i-1): if str[i-a] != str[i+1+a]: # print(1,i,a) if max < 2*a: max=2*a break elif (i - a == 0 and str[i - a] == str[i + 1 + a]): # print(1, i, a) if max < 2 * a +2: max = 2 * a +2 break if i < n-2 and str[i] == str[i+2]: for a in range(n-i-2): if str[i-a] != str[i+2+a]: # print(2, i, a) if max < 2*a+1: max = 2*a+1 break elif (i - a == 0 and str[i - a] == str[i + 2 + a]): # print(2, i, a) if max < 2 * a + 3: max = 2 * a + 3 break print(max) except: break