/************************************************
* Author        :Running_Time
* Created Time  :2015/11/1 14:58:49
* File Name     :J.cpp************************************************/#include <cstdio>
#include <algorithm>
#include <iostream>
#include <cstring>
#include <cmath>
#include <string>
#include <vector>
#include <queue>
#include <deque>
#include <stack>
#include <list>
#include <map>
#include <set>
#include <bitset>
#include <cstdlib>
#include <ctime>
using namespace std;#define lson l, mid, rt << 1
#define rson mid + 1, r, rt << 1 | 1
typedef long long ll;
const int N = 1e3 + 10;
const int INF = 0x3f3f3f3f;
const int MOD = 1e9 + 7;
struct Trie {int ch[N*30][2], sz;int cnt[N*30];void init(void) {sz = 1; ch[0][0] = ch[0][1] = 0;memset (cnt, 0, sizeof (cnt));}void insert(int x)  {int u = 0;for (int c, i=30; i>=0; --i)   {c = x & (1 << i) ? 1 : 0;if (!ch[u][c])  {ch[sz][0] = ch[sz][1] = 0;ch[u][c] = sz++;}u = ch[u][c];cnt[u]++;}}void remove(int x)  {int u = 0;for (int c, i=30; i>=0; --i)    {c = x & (1 << i) ? 1 : 0;u = ch[u][c];cnt[u]--;}}int query(int x)    {int u = 0;for (int c, i=30; i>=0; --i)   {c = x & (1 << i) ? 1 : 0;if (c == 1) {if (ch[u][0] && cnt[ch[u][0]])  u = ch[u][0];else    u = ch[u][1], x ^= (1 << i);}else    {if (ch[u][1] && cnt[ch[u][1]])  u = ch[u][1], x ^= (1 << i);else    u = ch[u][0];}}return x;}
}trie;
int a[N];int main(void)    {int T;  scanf ("%d", &T);while (T--) {int n;  scanf ("%d", &n);for (int i=1; i<=n; ++i)    {scanf ("%d", &a[i]);}int ans = 0;trie.init ();for (int i=1; i<=n; ++i)    {trie.insert (a[i]);}for (int i=1; i<=n; ++i)    {trie.remove (a[i]);for (int j=i+1; j<=n; ++j)  {trie.remove (a[j]);ans = max (ans, trie.query (a[i] + a[j]));trie.insert (a[j]);}trie.insert (a[i]);}printf ("%d\n", ans);}return 0;
}