Life Forms

题目描述

[problemUrl]: https://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&category=23&page=show_problem&problem=2048 [PDF](https://uva.onlinejudge.org/external/111/p11107.pdf) ![](https://cdn.luogu.com.cn/upload/vjudge_pic/UVA11107/04d93e51c97a330deab8430cb607f2afbc3177ff.png)

输入输出格式

输入格式

![](https://cdn.luogu.com.cn/upload/vjudge_pic/UVA11107/c54b66973020292d8ed80cd06601ceda1aac4fdd.png)

输出格式

![](https://cdn.luogu.com.cn/upload/vjudge_pic/UVA11107/e26377a358b98d53b4f9c85ad5183540f494ac69.png)

输入输出样例

输入样例 #1

3
abcdefg
bcdefgh
cdefghi
3
xxx
yyy
zzz
0

输出样例 #1

bcdefg
cdefgh
?