#include<bits/stdc++.h>
using namespace std;
/*
ios::sync_with_stdio(false);cin.tie(nullptr);cout.tie(nullptr);
*/
// #define int long long
#define ld long double
//#define INT __int128
#define eb(x) emplace_back(x)
#define fi first
#define se second
typedef long long LL;
typedef unsigned long long ULL;
typedef pair<long long, long long> PLL;
typedef pair<int, int> PII;
typedef pair<double, double> PDD;
const LL INF = 0x3f3f3f3f3f3f3f3f;
const int inf = 0x3f3f3f3f;
const LL mod = 1e9 + 7;
const ld eps = 1e-12;
const int N = 1e5 + 10, M = N + 10;
int n;
int a[N];
map<int,int>mp;

void solve(){
    cin>>n;
    mp.clear();
    for(int i=1;i<=n;i++){
        scanf("%d",&a[i]);
        mp[a[i]]++;
    }   
    int mx1=0,mx2=0;
    for(auto i:mp){
        if(i.second>mx1){
            mx2=mx1;
            mx1=i.second;
        }
        else if(i.second>mx2){
            mx2=i.second;
        }
    }
    int ans=mx1|mx2|((mx1&mx2)-1);
    cout<<ans<<endl;
}

signed main(){
    // ios::sync_with_stdio(false);cin.tie(nullptr);cout.tie(nullptr);
    int T=1,cas=1;
    cin>>T;
    while(T--){
        solve();
    }
    return 0;
}