package backjoon;

import java.io.BufferedReader;

import java.io.IOException;

import java.io.InputStreamReader;

// https://www.acmicpc.net/problem/2675

// 문자열 반복

public class _2675 {

public static void main(String[] args) throws IOException {

//memory 11536 runtime 96

BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

int T = Integer.parseInt(br.readLine());

for(int i = 0; i < T; i++) {

String[] str = br.readLine().split(" ");

// String to int

int R = Integer.parseInt(str[0]);

String S = str[1];

for(int j = 0; j < S.length(); j++) {

for(int k = 0; k < R; k++) {

System.out.print(S.charAt(j));

}

}

System.out.println();

}

}

}

/*

input

2

3 ABC

5 /HTP

output

AAABBBCCC

/////HHHHHTTTTTPPPPP

*/