{"trustable":false,"sections":[{"title":"","value":{"format":"MD","content":"姚队最近在研究回文串,就是正读和反读都一样的字符串,比如“( - v - )”或者“QAQ”。现在他想在一个字符串里找到一个特殊的子串,这个子串不仅是回文串,还是所有回文串里最长的。"}},{"title":"Input","value":{"format":"MD","content":"输入就一行,一个长度不超过1000的字符串,只包含英文大小写"}},{"title":"Output","value":{"format":"MD","content":"输出最长的回文字符串,如果有多个最长的,就输出最先出现的"}},{"title":"Sample Input","value":{"format":"MD","content":"abaca"}},{"title":"Sample Output","value":{"format":"MD","content":"aba"}},{"title":"Sample Input","value":{"format":"MD","content":"Kazak"}},{"title":"Sample Output","value":{"format":"MD","content":"aza"}}]}