A binary string is a string where each character is either 0 or 1. Two binary strings a and b of equal length are similar, if they have the same character in some position (there exists an integer i such that a_i = b_i). For example:

  * 10010 and 01111 are similar (they have the same character in position 4); 
  * 10010 and 11111 are similar; 
  * 111 and 111 are similar; 
  * 0110 and 1001 are not similar. 



You are given an integer n and a binary string s consisting of 2n-1 characters. Let's denote s[l..r] as the contiguous substring of s starting with l-th character and ending with r-th character (in other words, s[l..r] = s_l s_{l + 1} s_{l + 2} ... s_r).

You have to construct a binary string w of length n which is similar to all of the following strings: s[1..n], s[2..n+1], s[3..n+2], ..., s[n..2n-1].

Input

The first line contains a single integer t (1 ≤ t ≤ 1000) — the number of test cases.

The first line of each test case contains a single integer n (1 ≤ n ≤ 50).

The second line of each test case contains the binary string s of length 2n - 1. Each character s_i is either 0 or 1.

Output

For each test case, print the corresponding binary string w of length n. If there are multiple such strings — print any of them. It can be shown that at least one string w meeting the constraints always exists.

Example

Input


4
1
1
3
00000
4
1110000
2
101


Output


1
000
1010
00

Note

The explanation of the sample case (equal characters in equal positions are bold):

The first test case: 

  * 1 is similar to s[1..1] = 1. 



The second test case: 

  * 000 is similar to s[1..3] = 000; 
  * 000 is similar to s[2..4] = 000; 
  * 000 is similar to s[3..5] = 000. 



The third test case: 

  * 1010 is similar to s[1..4] = 1110; 
  * 1010 is similar to s[2..5] = 1100; 
  * 1010 is similar to s[3..6] = 1000; 
  * 1010 is similar to s[4..7] = 0000. 



The fourth test case: 

  * 00 is similar to s[1..2] = 10; 
  * 00 is similar to s[2..3] = 01. 
from collections import deque
from collections import OrderedDict
import math
 
import sys
import os
import threading
import bisect
 
import operator
 
import heapq
 
 
from atexit import register
from io import BytesIO
 
#sys.stdin = BytesIO(os.read(0, os.fstat(0).st_size))
#sys.stdout = BytesIO()
#register(lambda: os.write(1, sys.stdout.getvalue()))
 
 
import io
#input = io.BytesIO(os.read(0, os.fstat(0).st_size)).readline


from sys import stdin, stdout
#input = sys.stdin.readline
#input = stdin.buffer.readline
#print = stdout.write
#a = [int(x) for x in input().split()]


#import os,io
#input=io.BytesIO(os.read(0,os.fstat(0).st_size)).readline

import os
import sys
from io import BytesIO, IOBase

BUFSIZE = 8192
class FastIO(IOBase):
	newlines = 0
 
	def __init__(self, file):
		self._fd = file.fileno()
		self.buffer = BytesIO()
		self.writable = "x" in file.mode or "r" not in file.mode
		self.write = self.buffer.write if self.writable else None
 
	def read(self):
		while True:
			b = os.read(self._fd, max(os.fstat(self._fd).st_size, BUFSIZE))
			if not b:
				break
			ptr = self.buffer.tell()
			self.buffer.seek(0, 2), self.buffer.write(b), self.buffer.seek(ptr)
		self.newlines = 0
		return self.buffer.read()
 
	def readline(self):
		while self.newlines == 0:
			b = os.read(self._fd, max(os.fstat(self._fd).st_size, BUFSIZE))
			self.newlines = b.count(b"\n") + (not b)
			ptr = self.buffer.tell()
			self.buffer.seek(0, 2), self.buffer.write(b), self.buffer.seek(ptr)
		self.newlines -= 1
		return self.buffer.readline()
 
	def flush(self):
		if self.writable:
			os.write(self._fd, self.buffer.getvalue())
			self.buffer.truncate(0), self.buffer.seek(0)
 
 
class IOWrapper(IOBase):
	def __init__(self, file):
		self.buffer = FastIO(file)
		self.flush = self.buffer.flush
		self.writable = self.buffer.writable
		self.write = lambda s: self.buffer.write(s.encode("ascii"))
		self.read = lambda: self.buffer.read().decode("ascii")
		self.readline = lambda: self.buffer.readline().decode("ascii")
 
 
#sys.stdin, sys.stdout = IOWrapper(sys.stdin), IOWrapper(sys.stdout)

#sys.stdin = open("F:\PY\\test.txt", "r")
#input = lambda: sys.stdin.readline().rstrip("\r\n")
input = lambda: sys.stdin.readline().rstrip("\r\n")



for _ in range(int(input())):
    n = int(input())
    s = input()
    maxCount0 = 0
    maxCount1 = 1
    lCoun0, lCoun1 = 0, 0
    for i in range(2*n-1):
        if s[i]=='0':
            lCoun0+=1
            lCoun1=0
            maxCount0=max(maxCount0, lCoun0)
        else:
            lCoun1+=1
            lCoun0=0
            maxCount1=max(maxCount1, lCoun1)
    if maxCount0>=maxCount1:
        for i in range(n):
            print(0, sep="", end="")
    else:
        for i in range(n):
            print(1, sep="", end="")
    print()
        
    

'''
n = int(input())
lis = list(map(int, input().split()))
sumAr = 0
for i in range(n):
    sumAr+=lis[i]
k = (sumAr-(n*(n-1)//2))//n
dif = sumAr - (k*n+(n*(n-1)//2))

answer=[]
for i in range(n):
    if i<dif:
        print(k+i+1)
        #print(k+i+1, end=" ")
    else:
        print(k+i)
        #print(k+i, end=" ")

#print(*answer, sep=" ")
        
'''





sys.exit(0)

class Person:
    def __init__(self, name, age):
        self.name = name
        self.age = age

p1 = Person("heelo", 27)

print(help(Person))


age = 26
name = 'Swaroop'
print('Возрас {} -- {} лет'.format(name, age))
print(help(object))


'''
for _ in range(int(input())):
    
    n = int(input())
    ar = list(map(int, input().split()))
    dp = [0]*100005
    for i in range(n):
        dp[ar[i]]+=1
    ar.clear()
    for i in range(len(dp)):
        if dp[i]!=0:
            ar.append(dp[i])       
    ar.sort()
    maxC = ar[len(ar)-1]
    sumA = sum(ar)
    answer=0
    for i in range(len(ar)):
        if ar[i]==maxC:
            answer+=1
            sumA-=maxC
    answer-=1
    answer+= min(sumA//(maxC-1), len(ar)-1)
    print(answer)
    #sys.exit(0)   
         
    




def maxDisjointIntervals(list_):
    list_.sort(key=lambda x: x[1])
    print(list_[0][0], list_[0][1])
    r1 = list_[0][1]
    for i in range(1, len(list_)):
        l1 = list_[i][0]
        r2 = list_[i][1]
        if l1>r1:
            print(l1, r2)
            r1 = r2

if __name__ =="__main__1":
    N=4
    intervals = [[1, 4], [2, 3], [4,6], [8,9]]
    maxDisjointIntervals(intervals)
    
    '''
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    