Time Limit: 5000MS Memory Limit: 65536 K

## Description

Given a N-figures positive integer whose first figure is not 0.
You can remove M figures from it so the rest figures form a
(N-M)-figures positive integer whose first figure is not 0.
Can you tell me the minimal?
## Input

The first line of the input is the number of test cases.
For each case there is two lines.
The first line contains two integers N and M.
The second line contains a N-figures positive integer
whose first figure is not 0.
( 0 <= M < N <= 10^5 )
There is a blank line before each test case.
## Output

For each test case output the answer on a line.
## Sample Input

4
2 1
90
9 3
123123123
11 1
90019008798
11 3
90019008798
## Sample Output

9
112123
9001008798
19008798

## Source