Turtle gives you a string $$$s$$$, consisting of lowercase Latin letters.

Turtle considers a pair of integers $$$(i, j)$$$ ($$$1 \le i < j \le n$$$) to be a pleasant pair if and only if there exists an integer $$$k$$$ such that $$$i \le k < j$$$ and both of the following two conditions hold:

- $$$s_k \ne s_{k + 1}$$$;
- $$$s_k \ne s_i$$$ or $$$s_{k + 1} \ne s_j$$$.

Besides, Turtle considers a pair of integers $$$(i, j)$$$ ($$$1 \le i < j \le n$$$) to be a good pair if and only if $$$s_i = s_j$$$ or $$$(i, j)$$$ is a pleasant pair.

Turtle wants to reorder the string $$$s$$$ so that the number of good pairs is maximized. Please help him!

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

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

The second line of each test case contains a string $$$s$$$ of length $$$n$$$, consisting of lowercase Latin letters.

It is guaranteed that the sum of $$$n$$$ over all test cases does not exceed $$$2 \cdot 10^5$$$.
Output format:
For each test case, output the string $$$s$$$ after reordering so that the number of good pairs is maximized. If there are multiple answers, print any of them.
Example Input 0:
5
3
abc
5
edddf
6
turtle
8
pppppppp
10
codeforces

Example Output 0:
acb
ddedf
urtlet
pppppppp
codeforces

Notes:
In the first test case, $$$(1, 3)$$$ is a good pair in the reordered string. It can be seen that we can't reorder the string so that the number of good pairs is greater than $$$1$$$. bac and cab can also be the answer.

In the second test case, $$$(1, 2)$$$, $$$(1, 4)$$$, $$$(1, 5)$$$, $$$(2, 4)$$$, $$$(2, 5)$$$, $$$(3, 5)$$$ are good pairs in the reordered string. efddd can also be the answer.

Example input:
5
3
abc
5
edddf
6
turtle
8
pppppppp
10
codeforces


Example output:
acb
ddedf
urtlet
pppppppp
codeforces