Haku Kale now wants to loot in a global scale. For that he needs the help of some underground gang leaders. But the problem is, he does not know the name of any gang leader. After a deep research, he got the name of gang leaders in an encrypted form. After spending months in decrypting it, he found the way to decrypt the name of the leaders from the information he has gathered. But he doesn’t have time to decrypt it. So, he wants a programmer to write a program for him to decrypt those names within a second.
According to Haku Kale, “Each character of name of gang leader is hidden in different words. Those characters can be extracted from middle of those given words after arranging their letters in alphabetical order.”
 

Input
The first line of the input contains an integer T number of gang leaders. For each gang leader N is given which signifies the number of characters in gang leader name which are encrypted in N number of words of length W.
 

Output
Each line contains the name of gang leader.
 

Constraints
Should contain all the constraints on the input data that you may have. Format it like:

0 ≤ T ≤ 100
0 ≤ N ≤ 20
0 ≤ W ≤ 500

 

Example
Input:
2
3
ARCTV
ACADAPALA
ZHFGOSM
4
FJAOHVG
AAAAA
NUWRE
IAT

Output:
RAM
HARI
 

Explanation
Example Case 1. The name contains 3 characters as mentioned where first letter can be obtained from “ARCTV” after arranging them in alphabetical order, second letter can be obtained from “ACADAPALA” after arranging them in alphabetical order and so on.
Example Case 2. Similar to Case 1 but this time the name contains 4 characters.
t=input()
while t>0:
	n=input()
	B=[]
	for i in xrange(n):
		A=raw_input()
		A=sorted(A)
		B.append(A[len(A)/2])
	print "".join(B)
	t=t-1