输入一个字符串（字符串的长度不超过100），求出其中最长的回文子串的长度。子串的含义是：在原串中连续出现的字符串片段。回文的含义是：正着看和倒着看相同，如abba和yyxyy。-Enter a string (the length of the string is not more than 100), calculated the length of the longest palindrome substring. The substring meaning: the string frag