#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define ull unsigned long long
#define pii pair<int, int>
#define pb push_back

int n;
vector<ll> a, cnt;

ll get_id(int x){
    ll t = -1;
    while(x){
        t++;
        x >>= 1;
    }
    return t;
}
void slv(){
    int n;
    cin >> n;
    vector<int> a(n + 1), cnt(n + 1);
//    a.resize(n + 1), cnt.resize(n + 1);

    int f = 1;
    for(int i = 1; i <= n; ++i) cin >> a[i];
    for(int i = 2; i <= n; ++i) if(a[i] != a[i - 1]) f = 0;
    if(f){cout << n << '\n'; return;}

    for(int i = 1; i <= n; ++i) cnt[a[i]]++;

    ll id = -1, sum = 0, p = -1;
    for(int i = 1; i <= n; ++i){
        if(cnt[i] == 0) continue;
        id = max(id, get_id(cnt[i]));//cnt表示出现次数，我们要找位最高的
    }
    for(int i = 1; i <= n; ++i){
        if(get_id(cnt[i] == id)) sum++, p = i;//i出现次数最高
    }

    ll _ans = 0;
    if(sum > 1){
        for(int j = 0; j <= id; ++j) _ans = _ans + (1 << j);
        cout << _ans << '\n';
        return ;
    }

    //p是最高的id
    for(int i = 1; i <= n; ++i){
        ll ans = 0;
        if(cnt[i] == 0) continue;
        if(i == p) continue;
        ll x = cnt[p], y = cnt[i];
        for(int j = id; j >= 0; --j){
            int kx = ((x >> j) & 1), ky = ((y >> j) & 1);
            if(kx == 1 && ky == 1){
                for(int k = j; k >= 0; --k){
                    ans = ans + (1 << k);
                }
                break;
            }else if((kx == 1 && ky == 0) || (kx == 0 && ky == 1)){
                ans = ans + (1 << j);
            }else if(kx == 0 && ky == 0){
                ans = ans + 0;
            }
        }
        _ans = max(_ans, ans);
    }
    cout << _ans << '\n';
}

signed main(){
    // ios::sync_with_stdio(0), cin.tie(0);
    int _; cin >> _;
    while(_--) slv();
    return 0;
}
/*
2
7
1 2 3 4 3 2 1
9
1 1 1 1 1 2 2 2 2
*/