문자열 반복

import java.util.*;

class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int a = sc.nextInt();
        
        for(int i = 0 ; i < a ; i++){
            int b = sc.nextInt();
            String c = sc.next();
            
            for(int j = 0 ; j < c.length() ; j++){
                for(int k = 0 ; k < b ; k ++){
                    System.out.print(c.charAt(j));
                }       
            }
            System.out.println();
        }
    }
}