A16037. Cipher Shifer

There is a string $a$ (unknown to you), consisting of lowercase Latin letters, encrypted according to the following rule into string $s$ :

- after each character of string $a$ , an arbitrary (possibly zero) number of any lowercase Latin letters, different from the character itself, is added;
- after each such addition, the character that we supplemented is added.

You are given string $s$ , and you need to output the initial string $a$ . In other words, you need to decrypt string $s$ .

Note that each string encrypted in this way is decrypted uniquely.

The first line of the input contains a single integer $t$ ( $1 \le t \le 1000$ ) — the number of test cases.

The descriptions of the test cases follow.

The first line of each test case contains a single integer $n$ ( $2 \le n \le 100$ ) — the length of the encrypted message.

The second line of each test case contains a string $s$ of length $n$ — the encrypted message obtained from some string $a$ .

For each test case, output the decrypted message $a$ on a separate line.

In the first encrypted message, the letter $a$ is encrypted as $aba$ , and the letter $c$ is encrypted as $cabac$ .

In the second encrypted message, only one letter $q$ is encrypted as $qzxcq$ .

In the third encrypted message, zero characters are added to each letter.