#include <bits/stdc++.h>
using namespace std;
using i64 = long long;
#define mod 1'000'000'007

void solve()
{
    int n;
    cin >> n;
    vector<i64> s(64);
    while (n--)
    {
        i64 x;
        cin >> x;
        for (int j = 63; j >= 0; j--)
        {
            if (x >> j & 1)
            {
                if (s[j])
                    x ^= s[j];
                else
                {
                    s[j] = x;
                    x = 0;
                }
            }
        }
    }
    i64 ans = 0;
    for (int i = 63; i >= 0; i--)
        if ((ans ^ s[i]) > ans)
            ans ^= s[i];
    cout << ans << '\n';
}

signed main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    int t = 1;
    cin >> t;
    while (t--)
        solve();
}