2675

import java.util.*;

public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
    	
        int T = sc.nextInt();
        int R;
        String S;
        for(int i=0; i<T; i++) {
        	R = sc.nextInt();
        	S = sc.next();
        	repeat(R,S);
        }
        
        
        sc.close();
    }
    
    public static void repeat(int r, String s) {
    	char[] before = s.toCharArray();
    	
    	for(int i=0; i<s.length(); i++) {
    		for(int j=0; j<r; j++) {
    			System.out.print(before[i]);
    		}
    	}
    	System.out.println();
    }
		
}