#include <bits/stdc++.h>
using namespace std;
 
string operation1(string s){
	return s;
}
 
string operation2(string s){
	string temp = s;
	sort(s.rbegin(), s.rend());
	string temp2 = s + temp;
	return temp2;
}
 
 
int main() {
	int t; cin >> t;
	while(t--){
		int n; cin >> n;
		string s; cin >> s; int len = s.length();
		string final;
		if(s[0]-'a' <= s[len-1]-'a')
			final = operation1(s);
		else
			final = operation2(s);
		cout << final << endl;
	}
	return 0;
}

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

NQo0CmNwbQoyCmdyaWIKMTAKa3VwaXRpbWlsYWJsb2RhcmJ1egoxMDAwMDAwMDAwCmNhcHliYXJhCjYKYWJhY2FiYQo=

5
4
cpm
2
grib
10
kupitimilablodarbuz
1000000000
capybara
6
abacaba