Palindromic Subsequence

题目描述

[problemUrl]: https://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&category=26&page=show_problem&problem=2399 [PDF](https://uva.onlinejudge.org/external/114/p11404.pdf) ![](https://cdn.luogu.com.cn/upload/vjudge_pic/UVA11404/5a2f90597be3614b65fba8ea886ef3720ad90e24.png)

输入输出格式

输入格式

![](https://cdn.luogu.com.cn/upload/vjudge_pic/UVA11404/5d529bca5a84ba4c913ad766ed8b0f427f7ca32d.png)

输出格式

![](https://cdn.luogu.com.cn/upload/vjudge_pic/UVA11404/dfe827b1e9174c45126a7e12ff91c03e886b8913.png)

输入输出样例

输入样例 #1

aabbaabb
computer
abzla
samhita

输出样例 #1

aabbaa
c
aba
aha