找出最长的回文子串，输出的第一行为找到的最长的回文字符串的长度。后面的行应该包括该字符串，字符串两边多余的空格和标点都不需要输出，但字符串中的空格、标点和换行则需要按照原样输出。-To find the longest palindrome substring of the first acts of the output to find the longest palindrome length of the string. Back row should include extra spaces and punctuation of the strings on both sides do not need to output the string, but the string of spaces, punctuation and line breaks as is output.