#include <cstdio>
#include <cstdlib>
#include <iostream>
#include <cstring>
#include <string>
#include <algorithm>
#include <cmath>
#include <vector>
#include <queue>
#include <stack>
#include <deque>
#include <map>
#include <unordered_map>
#include <set>
#include <unordered_set>

using namespace std;
#define INF 1234567890

int main() {
	ios::sync_with_stdio(false);
	cin.tie(NULL);
	cout.tie(NULL);

	int _T = 0;
	cin >> _T;
	while (_T--)
	{
		string s;
		int n;
		cin >> n >> s;
		for (auto a : s) 
			for (int i = 0; i < n; i++)
				cout << a;
		cout << "\n";
		
	}

	return 0;
}