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: import java.io.BufferedReader;
  import java.io.BufferedWriter;
  import java.io.File;
  import java.io.FileReader;
  import java.io.FileWriter;
  import java.io.IOException;
  import java.io.InputStreamReader;
  import java.io.OutputStreamWriter;
  import java.io.PrintWriter;
  import java.lang.reflect.Array;
  import java.util.ArrayDeque;
  import java.util.ArrayList;
  import java.util.Arrays;
  import java.util.Collections;
  import java.util.Comparator;
  import java.util.Deque;
  import java.util.HashMap;
  import java.util.HashSet;
  import java.util.LinkedHashMap;
  import java.util.LinkedList;
  import java.util.List;
  import java.util.Map;
  import java.util.PriorityQueue;
  import java.util.Queue;
  import java.util.Random;
  import java.util.Set;
  import java.util.Stack;
  import java.util.StringTokenizer;
  import java.util.TreeSet;
  import java.util.stream.Collectors;
  
  public class Main {
      static int mod = (int) (1e9) + 7;
  
      /* ======================DSU===================== */
      static class dsu {
          static int parent[], n;// min[],value[];
          static long size[];
  
          dsu(int n) {
              parent = new int[n + 1];
              size = new long[n + 1];
              // min=new int[n+1];
              // value=new int[n+1];
              Main.dsu.n = n;
              makeSet();
          }
  
          static void makeSet() {
              for (int i = 1; i <= n; i++) {
                  parent[i] = i;
                  size[i] = 1;
                  // min[i]=i;
              }
          }
  
          static int find(int a) {
              if (parent[a] == a)
                  return a;
              else {
                  return parent[a] = find(parent[a]);// Path Compression
              }
          }
  
          static void union(int a, int b) {
              int setA = find(a);
              int setB = find(b);
              if (setA == setB)
                  return;
              if (size[setA] >= size[setB]) {
                  parent[setB] = setA;
                  size[setA] += size[setB];
              } else {
                  parent[setA] = setB;
                  size[setB] += size[setA];
              }
          }
      }
  
      /* ======================================================== */
      static class Pair<X extends Number, Y extends Number> implements Comparator<Pair> {
          X x;
          Y y;
  
          // Constructor
          public Pair(X x, Y y) {
              this.x = x;
              this.y = y;
          }
  
          public Pair() {
  
          }
  
          @Override
          public int compare(Main.Pair o1, Main.Pair o2) {
              return ((int) (o1.y.intValue() - o2.y.intValue()));// Ascending Order based on 'y'
          }
      }
  
      /* ===============================Tries================================= */
      static class TrieNode {
          private HashMap<Character, TrieNode> children = new HashMap<>();
          public int size;
          boolean endOfWord;
  
          public void putChildIfAbsent(char ch) {
              children.putIfAbsent(ch, new TrieNode());
          }
  
          public TrieNode getChild(char ch) {
              return children.get(ch);
          }
      }
  
      static private TrieNode root;
  
      public static void insert(String str) {
          TrieNode curr = root;
          for (char ch : str.toCharArray()) {
              curr.putChildIfAbsent(ch);
              curr = curr.getChild(ch);
              curr.size++;
          }
          // mark the current nodes endOfWord as true
          curr.endOfWord = true;
      }
  
      public static int search(String word) {
          TrieNode curr = root;
  
          for (char ch : word.toCharArray()) {
              curr = curr.getChild(ch);
              if (curr == null) {
                  return 0;
              }
          }
          // size contains words starting with prefix- word
          return curr.size;
      }
  
      public boolean delete(TrieNode current, String word, int index) {
          if (index == word.length()) {
              // when end of word is reached only delete if currrent.endOfWord is true.
              if (!current.endOfWord) {
                  return false;
              }
              current.endOfWord = false;
              // if current has no other mapping then return true
              return current.children.size() == 0;
          }
          char ch = word.charAt(index);
          TrieNode node = current.children.get(ch);
          if (node == null) {
              return false;
          }
          boolean shouldDeleteCurrentNode = delete(node, word, index + 1);
  
          // if true is returned then delete the mapping of character and trienode
          // reference from map.
          if (shouldDeleteCurrentNode) {
              current.children.remove(ch);
              // return true if no mappings are left in the map.
              return current.children.size() == 0;
          }
          return false;
      }
  
      /* ================================================================= */
      static class FastReader {
          BufferedReader br;
          StringTokenizer st;
  
          public FastReader() {
              br = new BufferedReader(new InputStreamReader(System.in));
          }
  
          String next() {
              while (st == null || !st.hasMoreElements()) {
                  try {
                      st = new StringTokenizer(br.readLine());
                  } catch (IOException e) {
                      e.printStackTrace();
                  }
              }
              return st.nextToken();
          }
  
          int nextInt() {
              return Integer.parseInt(next());
          }
  
          long nextLong() {
              return Long.parseLong(next());
          }
  
          double nextDouble() {
              return Double.parseDouble(next());
          }
  
          String nextLine() {
              String str = "";
              try {
                  str = br.readLine();
              } catch (IOException e) {
                  e.printStackTrace();
              }
              return str;
          }
  
          int[] intArr(int n) {
              int res[] = new int[n];
              for (int i = 0; i < n; i++)
                  res[i] = nextInt();
              return res;
          }
  
          long[] longArr(int n) {
              long res[] = new long[n];
              for (int i = 0; i < n; i++)
                  res[i] = nextLong();
              return res;
          }
      }
  
      static FastReader f = new FastReader();
      static BufferedWriter w = new BufferedWriter(new OutputStreamWriter(System.out));
  
      static boolean isPrime(long n) {
          if (n <= 1)
              return false;
          if (n <= 3)
              return true;
          if (n % 2 == 0 || n % 3 == 0)
              return false;
          for (long i = 5; i * i <= n; i = i + 6)
              if (n % i == 0 || n % (i + 2) == 0)
                  return false;
          return true;
      }
  
      static int lowerBound(int a[], int x) { // x is the target, returns lowerBound. If not found return -1
          int l = -1, r = a.length, flag = 0;
          while (l + 1 < r) {
              int m = (l + r) >>> 1;
              if (x == a[m])
                  flag = 1;
              if (a[m] >= x)
                  r = m;
              else
                  l = m;
          }
          return r;
      }
  
      static int upperBound(int a[], int x, int l, int r) {// x is the target, returns upperBound. If not found return -1
          int flag = 0;
          while (l + 1 < r) {
              int m = (l + r) >>> 1;
              if (a[m] == x)
                  return m;
              if (a[m] <= x) {
                  l = m;
                  flag = 1;
              } else
                  r = m;
          }
          return l + 1;
      }
  
      static long gcd(long a, long b) {
          if (a == 0)
              return b;
          return gcd(b % a, a);
      }
  
      static long lcm(long a, long b) {
          return (a * b) / gcd(a, b);
      }
  
      static long power(long x, long y) {
          long res = 1;
          while (y > 0) {
              if (y % 2 == 1)
                  res = (res * x);
              y >>= 1;
              x = (x * x);
          }
          return res;
      }
  
      public double binPow(double x, int n) {// binary exponentiation with negative power as well
          if (n == 0)
              return 1.0;
          double binPow = binPow(x, n / 2);
          if (n % 2 == 0) {
              return binPow * binPow;
          } else {
              return n > 0 ? (binPow * binPow * x) : (binPow * binPow / x);
          }
      }
  
      static long ceil(long x, long y) {
          return (x % y == 0 ? x / y : (x / y + 1));
      }
  
      /*
       * ===========Modular Operations==================
       */
      static long modPower(long x, long y, long p) {
          long res = 1;
          x = x % p;
          while (y > 0) {
              if (y % 2 == 1)
                  res = (res * x) % p;
              y = y >> 1; // y = y/2
              x = (x * x) % p;
          }
          return res;
      }
  
      static long modInverse(long n, long p) {
          return modPower(n, p - 2, p);
      }
  
      static long modAdd(long a, long b) {
          return ((a + b + mod) % mod);
      }
  
      static long modMul(long a, long b) {
          return ((a % mod) * (b % mod)) % mod;
      }
  
      static long[] fac = new long[200000 + 5];
      static long[] invFac = new long[200000 + 5];
  
      static long nCrModPFermat(int n, int r) {
          if (r == 0)
              return 1;
          // return (fac[n] * modInverse(fac[r], mod) % mod * modInverse(fac[n - r], mod)
          // % mod) % mod;
          return (fac[n] * invFac[r] % mod * invFac[n - r] % mod) % mod;
      }
  
      /*
       * ===============================================
       */
  
      static void ruffleSort(long[] a) {
          int n = a.length;
          Random r = new Random();
          for (int i = 0; i < a.length; i++) {
              int oi = r.nextInt(n);
              long temp = a[i];
              a[i] = a[oi];
              a[oi] = temp;
          }
          Arrays.sort(a);
      }
  
      static void ruffleSort(int[] a) {
          int n = a.length;
          Random r = new Random();
          for (int i = 0; i < a.length; i++) {
              int oi = r.nextInt(n);
              int temp = a[i];
              a[i] = a[oi];
              a[oi] = temp;
          }
          Arrays.sort(a);
      }
  
      static String binString32(int n) {
          StringBuilder str = new StringBuilder("");
          String bin = Integer.toBinaryString(n);
          if (bin.length() != 32) {
              for (int k = 0; k < 32 - bin.length(); k++) {
                  str.append("0");
              }
              str.append(bin);
          }
          return str.toString();
      }
  
      static class sparseTable {
          public static int st[][];
          public static int log = 4;
  
          static int func(int a, int b) {// make func as per question(here min range query)
              return (int) gcd(a, b);
          }
  
          void makeTable(int n, int a[]) {
  
              st = new int[n][log];
              for (int i = 0; i < n; i++) {
                  st[i][0] = a[i];
              }
              for (int j = 1; j < log; j++) {
                  for (int i = 0; i + (1 << j) <= n; i++) {
                      st[i][j] = func(st[i][j - 1], st[i + (1 << (j - 1))][j - 1]);
                  }
              }
          }
  
          static int query(int l, int r) {
              int length = r - l + 1;
              int k = 0;
              while ((1 << (k + 1)) <= length) {
                  k++;
              }
              return func(st[l][k], st[r - (1 << k) + 1][k]);
          }
  
          static void printTable(int n) {
              for (int j = 0; j < log; j++) {
                  for (int i = 0; i < n; i++) {
                      System.out.print(st[i][j] + " ");
                  }
                  System.out.println();
              }
          }
      }
  
      /*
       * ====================================Main=================================
       */
  
      // static int st[], a[];
  
      // static void buildTree(int treeIndex, int lo, int hi) {
      // if (hi == lo) {
      // st[treeIndex] = a[lo];
      // return;
      // }
      // int mid = (lo + hi) / 2;
      // buildTree(treeIndex * 2 + 1, lo, mid);
      // buildTree(treeIndex * 2 + 2, mid + 1, hi);
      // st[treeIndex] = merge(st[treeIndex * 2 + 1], st[treeIndex * 2 + 2]);
      // }
  
      // static void update(int treeIndex, int lo, int hi, int arrIndex, int val) {
      // if (hi == lo) {
      // st[treeIndex] = val;
      // a[arrIndex] = val;
      // return;
      // }
      // int mid = (hi + lo) / 2;
      // if (mid < arrIndex) {
      // update(treeIndex * 2 + 2, mid + 1, hi, arrIndex, val);
      // } else {
      // update(treeIndex * 2 + 1, lo, mid, arrIndex, val);
      // }
      // st[treeIndex] = merge(st[treeIndex * 2 + 1], st[treeIndex * 2 + 2]);
      // }
  
      // static int query(int treeIndex, int lo, int hi, int l, int r) {
      // if (l <= lo && r >= hi) {
      // return st[treeIndex];
      // }
      // if (l > hi || r < lo) {
      // return 0;
      // }
      // int mid = (hi + lo) / 2;
      // return query(treeIndex * 2 + 1, lo, mid, l, Math.min(mid, r));
      // }
  
      // static int merge(int a, int b) {
      // return a + b;
      // }
  
      public static long findKthPositive(long[] A, long k) {
          int l = 0, r = A.length, m;
          while (l < r) {
              m = (l + r) / 2;
              if (A[m] - 1 - m < k)
                  l = m + 1;
              else
                  r = m;
          }
          return l + k;
      }
  
      static int[] z_function(char ar[]) {
          int[] z = new int[ar.length];
          z[0] = ar.length;
          int l = 0;
          int r = 0;
          for (int i = 1; i < ar.length; i++) {
              if (r < i) {
                  l = i;
                  r = i;
                  while (r < ar.length && ar[r - l] == ar[r])
                      r++;
                  z[i] = r - l;
                  r--;
              } else {
                  int k = i - l;
                  if (z[k] < r - i + 1) {
                      z[i] = z[k];
                  } else {
                      l = i;
                      while (r < ar.length && ar[r - l] == ar[r])
                          r++;
                      z[i] = r - l;
                      r--;
                  }
              }
          }
          return z;
      }
  
      // BINARY SEARCH
      // count of set bits in a particular position
      // suffix max array/ suffix sum array/ prefix
      static long min, dp[][];
      static ArrayList<Integer> mask;
      static long ans;
  
      public static void main(String args[]) throws Exception {
          int t = 1;
          t = f.nextInt();
          int tc = 1;
          // fac[0] = 1;
          // for (int i = 1; i <= 200000; i++) {
          // fac[i] = fac[i - 1] * i % mod;
          // invFac[i] = modInverse(fac[i], mod);
          // }
          while (t-- != 0) {
              int n=f.nextInt();
              int a[]=new int[n];
              a=f.intArr(n);
              int max=0,min=Integer.MAX_VALUE;
              int and=a[0];
              for(int i:a){
                  and=and&i;
              }
              w.write((and)+"\n");
          }
          w.flush();
      }
  }
  /*
   *
   */