CF1700B.Palindromic Numbers

During a daily walk Alina noticed a long number written on the ground. Now Alina wants to find some positive number of same length without leading zeroes, such that the sum of these two numbers is a palindrome.

Recall that a number is called a palindrome, if it reads the same right to left and left to right. For example, numbers $121, 66, 98989$ are palindromes, and $103, 239, 1241$ are not palindromes.

Alina understands that a valid number always exist. Help her find one!

阿尔伊娜在日常散步时注意到地上写了一个很长的数字。现在，阿尔伊娜想找到一个正整数，其位数与该数字相同且不以 0 开头，使得这两个数之和是一个回文数。

回忆一下：若一个数从左到右读与从右到左读完全相同，则称其为回文数。例如，$121$、$66$、$98989$ 是回文数，而 $103$、$239$、$1241$ 不是回文数。

阿尔伊娜知道，满足条件的数一定存在。请帮她找出一个！

The first line of input data contains an integer $t$ ($1 \leq t \leq 100$) — the number of test cases. Next, descriptions of $t$ test cases follow.

The first line of each test case contains a single integer $n$ ($2 \leq n \leq 100\,000$) — the length of the number that is written on the ground.

The second line of contains the positive $n$-digit integer without leading zeroes — the number itself.

It is guaranteed that the sum of the values $n$ over all test cases does not exceed $100\,000$.

输入数据的第一行包含一个整数 $t$（$1 \leq t \leq 100$），表示测试用例的数量。接下来是 $t$ 个测试用例的描述。

每个测试用例的第一行包含一个整数 $n$（$2 \leq n \leq 100\,000$），表示写在地面上的数字的长度。

每个测试用例的第二行包含一个 $n$ 位正整数（无前导零），即该数字本身。

保证所有测试用例的 $n$ 值之和不超过 $100\,000$。

For each of $t$ test cases print an answer — a positive $n$-digit integer without leading zeros, such that the sum of the input integer and this number is a palindrome.

We can show that at least one number satisfying the constraints exists. If there are multiple solutions, you can output any of them.

对于 $t$ 个测试用例中的每一个，输出一个答案——一个不含前导零的正 $n$ 位整数，使得该整数与输入整数之和为回文数。

可以证明，至少存在一个满足约束条件的数。若存在多个解，输出其中任意一个即可。

In the first test case $99 + 32 = 131$ is a palindrome. Note that another answer is $12$, because $99 + 12 = 111$ is also a palindrome.

In the second test case $1023 + 8646 = 9669$.

In the third test case $385 + 604 = 989$.

在第一个测试用例中，$99 + 32 = 131$ 是一个回文数。注意，另一个答案是 $12$，因为 $99 + 12 = 111$ 也是一个回文数。

在第二个测试用例中，$1023 + 8646 = 9669$。

在第三个测试用例中，$385 + 604 = 989$。