Z. Nonexistent
time limit per test
2 seconds
memory limit per test
1024 megabytes
input
standard input
output
standard output

You are given a binary string $$$s$$$ of length $$$2n-1$$$.

For each test case, output a binary string $$$t$$$ of length $$$n$$$ such that $$$t$$$ is not a subsequence of $$$s$$$.

Recall that a string $$$a$$$ is a subsequence of a string $$$b$$$ if and only if $$$a$$$ can be obtained from $$$b$$$ by deleting zero or more characters without changing the order of the remaining characters.

It can be proven that under the given constraints, at least one valid answer always exists.

Input

Each test contains multiple test cases. The first line contains the number of test cases $$$t$$$ ($$$1 \le t \le 2\cdot 10^4$$$). The description of the test cases follows.

The first line of each test case contains a single integer $$$n$$$ ($$$1\le n\le 2\cdot 10^5$$$).

The second line of each test case contains a binary string $$$s$$$ of length $$$2n-1$$$.

It is guaranteed that the sum of $$$n$$$ over all test cases does not exceed $$$2\cdot 10^5$$$.

Output

For each test case, output a binary string $$$t$$$ of length $$$n$$$ such that $$$t$$$ is not a subsequence of $$$s$$$.

If there are multiple valid answers, print any of them.

Each answer may be printed on its own line.

Example
Input
5
1
0
2
101
3
00110
4
0101100
5
111001001
Output
1
00
101
0001
00110