human
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. 
Solve the task in PYTHON3.

Can you provide a Python code to print the corresponding binary string w of length n?
assistant
#Here is Python code to print the corresponding binary string w of length n.

from collections import defaultdict as dc
import sys
from collections import Counter as cnt
from collections import deque as dq
from copy import copy,deepcopy
import itertools 
import math
mod=10**9 +7
# How to sort a list using two compare :
# instead of defining a function define class as a key
# class key(str):
#     def __lt__(x,y):
#         return int(x+y)>int(y+x)
def sinp():
    p=str(sys.stdin.readline())
    return p

def seive(n):
    p=[0]*(n+1)
    for i in range(2,n):           
        for j in range(2*i,n+1,i):
                p[i]=1
    return p

def inp(): 
    p=int(sys.stdin.readline())
    return p

def line():
    p=list(map(int,sys.stdin.readline().split()))
    return p

def read_mat():
    n=inp()
    a=[]
    for i in range(n):
        a.append(line())
    return a

def ind(a):
    return ord(a)-ord('A')

def digit(n):
    p=[int(i) for i in str(n)]
    return p

def check(p,n):
    l=str(p)
    s=''
    for i in range(n):
        s=s+bin(int(l[i]))[2:]
    s=s[:-n]
    if s=='':
        return 0
    return int(s,2)

def createcomb(a,n,i):
    if i==n:
        ans.append(a)
    else:
        for z in range(n):
            a.append(a[z])
            createcomb(a,n,z)  
            a.pop()          

def solve(a,n,a1,b1,c1):
    l=[]
    r=[]
    x=0
    for i in range(n):
        if a[i]>=x:
            l.append(i)
            x=a[i]
    x=0
    for i in range(n-1,-1,-1):
        if a[i]>=x:
            r.append(i)
            x=a[i]
    z=cnt(r)
    c=0
    p=len(l)
    q=len(r)
    for i in l:
        if z[i]:
            c+=1
    if p==a1 and q==b1 and c1==c:
        return 1
    return 0

def xor(a,b):
    s=''
    for i in range(len(a)):
        if a[i]=='1' and b[i]=='0':
            s+='1'
        elif b[i]=='1' and a[i]=='0':
            s+='1'
        else:
            s+='0'
    return s
for t in range(inp()):
    n=inp()
    a=str(input())
    s=''
    for i in range(len(a)-n+1):
        s+=a[i:i+n][i]
    print(s)