Lee was cleaning his house for the party when he found a messy string under the carpets. Now he'd like to make it clean accurately and in a stylish way...

The string s he found is a binary string of length n (i. e. string consists only of 0-s and 1-s).

In one move he can choose two consecutive characters s_i and s_{i+1}, and if s_i is 1 and s_{i + 1} is 0, he can erase exactly one of them (he can choose which one to erase but he can't erase both characters simultaneously). The string shrinks after erasing.

Lee can make an arbitrary number of moves (possibly zero) and he'd like to make the string s as clean as possible. He thinks for two different strings x and y, the shorter string is cleaner, and if they are the same length, then the lexicographically smaller string is cleaner.

Now you should answer t test cases: for the i-th test case, print the cleanest possible string that Lee can get by doing some number of moves.

Small reminder: if we have two strings x and y of the same length then x is lexicographically smaller than y if there is a position i such that x_1 = y_1, x_2 = y_2,..., x_{i - 1} = y_{i - 1} and x_i < y_i.

Input

The first line contains the integer t (1 ≤ t ≤ 10^4) — the number of test cases. 

Next 2t lines contain test cases — one per two lines.

The first line of each test case contains the integer n (1 ≤ n ≤ 10^5) — the length of the string s.

The second line contains the binary string s. The string s is a string of length n which consists only of zeroes and ones.

It's guaranteed that sum of n over test cases doesn't exceed 10^5.

Output

Print t answers — one per test case.

The answer to the i-th test case is the cleanest string Lee can get after doing some number of moves (possibly zero).

Example

Input


5
10
0001111111
4
0101
8
11001101
10
1110000000
1
1


Output


0001111111
001
01
0
1

Note

In the first test case, Lee can't perform any moves.

In the second test case, Lee should erase s_2.

In the third test case, Lee can make moves, for example, in the following order: 11001101 → 1100101 → 110101 → 10101 → 1101 → 101 → 01.
"""Template for Python Competitive Programmers prepared by pa.n.ik, kabeer seth and Mayank Chaudhary """

# to use the print and division function of Python3
from __future__ import division, print_function

"""value of mod"""
MOD = 998244353
mod = 10**9 + 7

"""use resource"""
# import resource
# resource.setrlimit(resource.RLIMIT_STACK, [0x100000000, resource.RLIM_INFINITY])

"""for factorial"""

def prepare_factorial():
    fact = [1]
    for i in range(1, 200005):
        fact.append((fact[-1] * i) % mod)
    ifact = [0] * 200005
    ifact[200004] = pow(fact[200004], mod - 2, mod)
    for i in range(200004, 0, -1):
        ifact[i - 1] = (i * ifact[i]) % mod

    return fact, ifact

"""uncomment next 4 lines while doing recursion based question"""
# import threading
# threading.stack_size(1<<27)
import sys
# sys.setrecursionlimit(10000)


"""uncomment modules according to your need"""
from bisect import bisect_left, bisect_right, insort
# from itertools import repeat
from math import floor, ceil, sqrt, degrees, atan, pi, log, sin, radians
from heapq import heappop, heapify, heappush
# from random import randint as rn
# from Queue import Queue as Q
from collections import Counter, defaultdict, deque
# from copy import deepcopy
# from decimal import *
# import re
# import operator


def modinv(n, p):
    return pow(n, p - 2, p)

def ncr(n, r,  fact, ifact):    # for using this uncomment the lines calculating fact and ifact
    t = (fact[n] * (ifact[r]*ifact[n-r]) % MOD)% MOD
    return t


def get_ints(): return map(int, sys.stdin.readline().strip().split())
def get_array(): return list(map(int, sys.stdin.readline().strip().split()))
def input(): return sys.stdin.readline().strip()

"""*****************************************************************************************"""

def GCD(x, y):
    while (y):
        x, y = y, x % y
    return x

def lcm(x, y):
    return (x * y)//(GCD(x, y))

def get_xor(n):
    return [n, 1, n+1, 0][n % 4]

def fast_expo(a, b):
    res = 1
    while b:
        if b&1:
            res = (res * a)
            res %= MOD
            b -= 1
        else:
            a = (a* a)
            a %= MOD
            b>>=1
    res %= MOD
    return res

def get_n(Sum):    # this function returns the maximum n for which Summation(n) <= Sum

    ans = (-1 + sqrt(1 + 8*Sum))//2
    return ans

""" ********************************************************************************************* """


def main():

    T = int(input())
    while T:
        n = int(input())
        string = input()

        if all(i == '1' for i in string) or all(i == '0' for i in string):
            print(string)
            T -= 1
            continue

        first_one = 0
        for index, value in enumerate(string):
            if value == '1':
                first_one = index
                break
        last_zero = n
        for i in range(n-1, -1, -1):
            if string[i] == '0':
                last_zero = i
                break

        if first_one > last_zero :
            print(string)
            T -= 1
            continue

        ans = []
        for i in range(first_one):
            ans.append(string[i])
        ans.append('0')
        for i in range(last_zero + 1, n):
            ans.append(string[i])

        print(''.join(ans))
        T -= 1


""" -------- Python 2 and 3 footer by Pajenegod and c1729 ---------"""

py2 = round(0.5)
if py2:
    from future_builtins import ascii, filter, hex, map, oct, zip
    range = xrange

import os, sys
from io import IOBase, BytesIO

BUFSIZE = 8192

class FastIO(BytesIO):
    newlines = 0

    def __init__(self, file):
        self._file = file
        self._fd = file.fileno()
        self.writable = "x" in file.mode or "w" in file.mode
        self.write = super(FastIO, self).write if self.writable else None

    def _fill(self):
        s = os.read(self._fd, max(os.fstat(self._fd).st_size, BUFSIZE))
        self.seek((self.tell(), self.seek(0, 2), super(FastIO, self).write(s))[0])
        return s

    def read(self):
        while self._fill(): pass
        return super(FastIO, self).read()

    def readline(self):
        while self.newlines == 0:
            s = self._fill();
            self.newlines = s.count(b"\n") + (not s)
        self.newlines -= 1
        return super(FastIO, self).readline()

    def flush(self):
        if self.writable:
            os.write(self._fd, self.getvalue())
            self.truncate(0), self.seek(0)


class IOWrapper(IOBase):

    def __init__(self, file):
        self.buffer = FastIO(file)
        self.flush = self.buffer.flush
        self.writable = self.buffer.writable
        if py2:
            self.write = self.buffer.write
            self.read = self.buffer.read
            self.readline = self.buffer.readline
        else:
            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)
input = lambda: sys.stdin.readline().rstrip('\r\n')

# sys.stdin = open('input.txt', 'r')
# sys.stdout = open('output.txt', 'w')

""" main function"""

if __name__ == '__main__':
    main()
    # threading.Thread(target=main).start()