description: Mocha is a young girl from high school. She has learned so much interesting knowledge from her teachers, especially her math teacher. Recently, Mocha is learning about binary system and very interested in bitwise operation.
  
  This day, Mocha got a sequence a of length n. In each operation, she can select an arbitrary interval [l, r] and for all values i (0≤ i ≤ r-l), replace a_{l+i} with a_{l+i}  \&  a_{r-i} at the same time, where \& denotes the [bitwise AND operation](https://en.wikipedia.org/wiki/Bitwise_operation#AND). This operation can be performed any number of times.
  
  For example, if n=5, the array is [a_1,a_2,a_3,a_4,a_5], and Mocha selects the interval [2,5], then the new array is [a_1,a_2 \&  a_5, a_3 \&  a_4, a_4 \&  a_3, a_5 \&  a_2].
  
  Now Mocha wants to minimize the maximum value in the sequence. As her best friend, can you help her to get the answer?
  
  Input
  
  Each test contains multiple test cases. 
  
  The first line contains a single integer t (1 ≤ t ≤ 100) — the number of test cases. Each test case consists of two lines.
  
  The first line of each test case contains a single integer n (1 ≤ n ≤ 100) — the length of the sequence.
  
  The second line of each test case contains n integers a_1, a_2, …, a_n (0 ≤ a_i ≤ 10^9).
  
  Output
  
  For each test case, print one integer — the minimal value of the maximum value in the sequence.
  
  Example
  
  Input
  
  
  4
  2
  1 2
  3
  1 1 3
  4
  3 11 3 7
  5
  11 7 15 3 7
  
  
  Output
  
  
  0
  1
  3
  3
  
  Note
  
  In the first test case, Mocha can choose the interval [1,2], then the sequence becomes [ 0, 0], where the first element is 1 \& 2, and the second element is 2 \& 1.
  
  In the second test case, Mocha can choose the interval [1,3], then the sequence becomes [ 1,1,1], where the first element is 1 \& 3, the second element is 1 \& 1, and the third element is 3 \& 1.
solution: 
  # Author : raj1307 - Raj Singh
  # Date   : 15.08.2021
  
  from __future__ import division, print_function
  
  import os,sys
  from io import BytesIO, IOBase
  
  if sys.version_info[0] < 3:
      from __builtin__ import xrange as range
      from future_builtins import ascii, filter, hex, map, oct, zip
  
  
  def ii():  return int(input())
  def si():  return input()
  def mi():  return map(int,input().strip().split(" "))
  def msi(): return map(str,input().strip().split(" "))
  def li():  return list(mi())
  
  def dmain():
      sys.setrecursionlimit(1000000)
      threading.stack_size(1024000)
      thread = threading.Thread(target=main)
      thread.start()
      
  #from collections import deque, Counter, OrderedDict,defaultdict
  #from heapq import nsmallest, nlargest, heapify,heappop ,heappush, heapreplace
  #from math import log,sqrt,factorial,cos,tan,sin,radians
  #from bisect import bisect,bisect_left,bisect_right,insort,insort_left,insort_right
  #from decimal import *
  #import threading
  #from itertools import permutations
  #Copy 2D list  m = [x[:] for x in mark] .. Avoid Using Deepcopy
  
  abc='abcdefghijklmnopqrstuvwxyz'
  abd={'a': 0, 'b': 1, 'c': 2, 'd': 3, 'e': 4, 'f': 5, 'g': 6, 'h': 7, 'i': 8, 'j': 9, 'k': 10, 'l': 11, 'm': 12, 'n': 13, 'o': 14, 'p': 15, 'q': 16, 'r': 17, 's': 18, 't': 19, 'u': 20, 'v': 21, 'w': 22, 'x': 23, 'y': 24, 'z': 25}
  mod=1000000007
  #mod=998244353
  inf = float("inf")
  vow=['a','e','i','o','u']
  dx,dy=[-1,1,0,0,1,-1,1,-1],[0,0,1,-1,1,-1,-1,1]
  def getKey(item): return item[1] 
  def sort2(l):return sorted(l, key=getKey,reverse=True)
  def d2(n,m,num):return [[num for x in range(m)] for y in range(n)]
  def isPowerOfTwo (x): return (x and (not(x & (x - 1))) )
  def decimalToBinary(n): return bin(n).replace("0b","")
  def ntl(n):return [int(i) for i in str(n)]
  def ncr(n,r): return factorial(n)//(factorial(r)*factorial(max(n-r,1)))
  
  def ceil(x,y):
      if x%y==0:
          return x//y
      else:
          return x//y+1
  
  def powerMod(x,y,p):
      res = 1
      x %= p
      while y > 0:
          if y&1:
              res = (res*x)%p
          y = y>>1
          x = (x*x)%p
      return res
  
  def gcd(x, y):
      while y:
          x, y = y, x % y
      return x
      
  def isPrime(n) : # Check Prime Number or not 
      if (n <= 1) : return False
      if (n <= 3) : return True
      if (n % 2 == 0 or n % 3 == 0) : return False
      i = 5
      while(i * i <= n) : 
          if (n % i == 0 or n % (i + 2) == 0) : 
              return False
          i = i + 6
      return True
  
  
  
  def read():
      sys.stdin  = open('input.txt', 'r')  
      sys.stdout = open('output.txt', 'w') 
  
  
  
  
  def main():
  
  
      
      for _ in range(ii()):
  
          
          n=ii()
          a=li()
          ans=a[0]
          for i in range(n):
              ans=ans&a[i]
          print(ans)
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
      
      
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
          
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  # region fastio
  # template taken from https://github.com/cheran-senthil/PyRival/blob/master/templates/template.py
  
  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")
  
  
  def print(*args, **kwargs):
      """Prints the values to a stream, or to sys.stdout by default."""
      sep, file = kwargs.pop("sep", " "), kwargs.pop("file", sys.stdout)
      at_start = True
      for x in args:
          if not at_start:
              file.write(sep)
          file.write(str(x))
          at_start = False
      file.write(kwargs.pop("end", "\n"))
      if kwargs.pop("flush", False):
          file.flush()
  
  
  if sys.version_info[0] < 3:
      sys.stdin, sys.stdout = FastIO(sys.stdin), FastIO(sys.stdout)
  else:
      sys.stdin, sys.stdout = IOWrapper(sys.stdin), IOWrapper(sys.stdout)
  
  input = lambda: sys.stdin.readline().rstrip("\r\n")
  
  # endregion
  
  
  if __name__ == "__main__":
      #read()
      main()
      #dmain()
  
  # Comment Read()
  