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A8348 | Luck is in Numbers

时间限制1s
内存限制256MB
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题目描述

The first line contains the number of the ticket that consists of $k$ characters ( $k=2n,1<=n<=10^{5}$ ).

输入格式

Print the number of the sought ticket or "-1" (without the quotes) if no such ticket exists.

输出格式

无

输入输出样例

输入 #1
13
输出 #1
20
输入 #2
2345
输出 #2
2348
输入 #3
88
输出 #3
-1
C++ 编辑器
输入
输出