1112 Stucked Keyboard

Statement

Metadata

作者: CHEN, Yue
单位: 浙江大学
代码长度限制: 16 KB
时间限制: 400 ms
内存限制: 64 MB

On a broken keyboard, some of the keys are always stucked. So when you type some sentences, the characters corresponding to those keys will appear repeatedly on screen for $k$ times.

Now given a resulting string on screen, you are supposed to list all the possible stucked keys, and the original string.

Notice that there might be some characters that are typed repeatedly. The stucked key will always repeat output for a fixed $k$ times whenever it is pressed. For example, when $k = 3$ , from the string thiiis iiisss a teeeeeest we know that the keys i and e might be stucked, but s is not even though it appears repeatedly sometimes. The original string could be this isss a teest.

Input Specification

Each input file contains one test case. For each case, the 1^st line gives a positive integer $k$ ( $1 < k \le 100$ ) which is the output repeating times of a stucked key. The 2^nd line contains the resulting string on screen, which consists of no more than 1000 characters from {a-z}, {0-9} and _. It is guaranteed that the string is non-empty.

Output Specification

For each test case, print in one line the possible stucked keys, in the order of being detected. Make sure that each key is printed once only. Then in the next line print the original string. It is guaranteed that there is at least one stucked key.

Sample Input

3
caseee1__thiiis_iiisss_a_teeeeeest

Sample Output

ei
case1__this_isss_a_teest

Last update: May 4, 2022