Background

Do this problem:

Problem Description

Given a string $A$ of length $n$.

• If $A_{i-1}=A_{i+1}$, then $A_i$ is called "erasable".

Define one operation as: erase all "erasable" characters in $A$.

Please output $A$ after performing the operation $k$ times.

Input Format

The first line contains two positive integers $T,id$, representing the number of test cases and the subtask ID.

For each test case, the first line contains a positive integer $n$ and an integer $k$.

The next line contains a string of length $n$.

Output Format

For each test case, output one line with a string representing the answer.

3 0
3 1
aba
5 2
acaca
3 0
abc

aa
aa
abc

Hint

Explanation of the samples:

• For the $1$-st test case, the string is $\text{aba}$, and after one operation it becomes $\text{aa}$.
• For the $2$-nd test case, the string is $\text{acaca}$, and after one operation it becomes $\text{aa}$, and after two operations it becomes $\text{aa}$.
• For the $3$-rd test case, the string is $\text{abc}$, and after zero operations it is $\text{abc}$.

"This problem uses bundled testdata."

For $100\%$ of the testdata, $1 \le \sum n \le 10^7$, $1 \le T \le 10^5$, $0\le k\le 10^{18}$, and the strings consist of lowercase letters.

Special property $\text{A}$: $A$ is a permutation of $\text{a}\sim\text{z}$.

Special property $\text{B}$: $\forall i\in[1,n-2], A_i= A_{i+2}$.

Special property $\text{C}$: It is guaranteed that each $A_i$ can only take two possible values.

Translated by ChatGPT 5