Solve the programming task below in a Python markdown code block.
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You are given a multi-set S of N integers, and an integer K. You want to find the maximum value of minimal excluded non-negative integer (MEX) of the multi-set given that you are allowed to add at most any K integers to the multi-set. Find the maximum value of MEX that you can obtain. 

Few examples of finding MEX of a multi-set are as follows. MEX of multi-set {0} is 1, {1} is 0, {0, 1, 3} is 2, {0, 1, 2, 3, 5, 6} is 4.

------ Input ------ 

The first line of the input contains an integer T denoting the number of testcases.

The first line of each test case contains two space seperated integers N and K denoting the size of the multi-set and the maximum number of extra integers that you can add in the multi-set respectively.

The second line contains N space separated integers denoting the multi-set S: S_{1}, S_{2} ,.... S_{N}.

------ Output ------ 

For each testcase, output the answer in a single line. 

------ Constraints ------ 

1 ≤ T ≤ 10
1 ≤ N ≤ 10^{5}
0 ≤ K ≤ 10^{5}
0 ≤ S_{i} ≤ 2 * 10^{5}

------ Subtasks ------ 

Subtask #1 (15 points): K=0.
Subtask #2 (85 points): Original Constraints.

----- Sample Input 1 ------ 
4

3 0

1 0 2

3 1

1 0 2

4 3

2 5 4 9

2 0

3 4
----- Sample Output 1 ------ 
3

4

6

0
----- explanation 1 ------ 
Example case 1. As K = 0, so we can't add any element to the multi-set. Elements of the set are {1, 0, 2}. The MEX value of this set is 3.
Example case 2. As K = 1, you are allowed to add at most 1 element to the multi-set. The multi-set are {1, 0, 2}. You can add element 3 to the multi-set, and it becomes {1, 0, 2, 3}. The MEX value of this multi-set is 4. There is no other way to have higher value of MEX of the set by adding at most one element to the multi-set.