Mr. Kitayuta's Gift

题意翻译

请加上一个小写字母使得字符串回文。如果可以，输出回文数；否则，输出NA。

题目描述

Mr. Kitayuta has kindly given you a string $ s $ consisting of lowercase English letters. You are asked to insert exactly one lowercase English letter into $ s $ to make it a palindrome. A palindrome is a string that reads the same forward and backward. For example, "noon", "testset" and "a" are all palindromes, while "test" and "kitayuta" are not. You can choose any lowercase English letter, and insert it to any position of $ s $ , possibly to the beginning or the end of $ s $ . You have to insert a letter even if the given string is already a palindrome. If it is possible to insert one lowercase English letter into $ s $ so that the resulting string will be a palindrome, print the string after the insertion. Otherwise, print "NA" (without quotes, case-sensitive). In case there is more than one palindrome that can be obtained, you are allowed to print any of them.

输入输出格式

输入格式

The only line of the input contains a string $ s $ ( $ 1<=|s|<=10 $ ). Each character in $ s $ is a lowercase English letter.

输出格式

If it is possible to turn $ s $ into a palindrome by inserting one lowercase English letter, print the resulting string in a single line. Otherwise, print "NA" (without quotes, case-sensitive). In case there is more than one solution, any of them will be accepted.

输入输出样例

输入样例 #1

revive

输出样例 #1

reviver

输入样例 #2

ee

输出样例 #2

eye

输入样例 #3

kitayuta

输出样例 #3

NA

说明

For the first sample, insert 'r' to the end of "revive" to obtain a palindrome "reviver". For the second sample, there is more than one solution. For example, "eve" will also be accepted. For the third sample, it is not possible to turn "kitayuta" into a palindrome by just inserting one letter.