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. 
def g
=====
What is 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.
et_inverter(n):
    max = (1<<n) - 1
    def inv(x): return max-x
    return inv
    # """invert each bit of unsigned integer x"""
    # pow2 = 1<<n
    # def inv(x):
    #     return ~(x+pow2) & ((pow2<<1)-1)
    # return inv

def controller(n, s):
    inv = get_inverter(n)
    excludes = [inv(int(s[i:i+n],base=2)) for i in range(n)]
    b = 0
    a = max_val = (1<<n)-1
    for x in excludes:
        if a > x:
            a = x
        if b < x:
            b = x
    if a > 0:
        return '0'*n
    if b < max_val:
        return '1'*n
    excludes = set(excludes)
    for x in range(1,n):
        if x not in excludes:
            return ('{:0%sb}' % n).format(x)
    return excludes

def c_in():
    try:
        import sys
        sys.stdin = open(sys.argv[0] + "/../in-a.txt")
    except:
        pass
    n_test_case = int(input())
    for i in range(n_test_case):
        n = int(input())
        s = input().rstrip()
        print(controller(n,s))

if __name__ == '__main__':
    c_in()