#include<iostream>
#include<cmath>
#include<iomanip>
#include<algorithm>
#include<cstdlib>
#include<cstring>
#include<vector>
#include<utility>

#define ll long long
#define sz(x) int(x.size())
#define all(x) x.begin(),x.end()
using namespace std;

void Fast_IO(){
    ios_base::sync_with_stdio(false), cin.tie(nullptr), cout.tie(nullptr);
    #ifndef ONLINE_JUDGE
        freopen("input.txt", "r", stdin), freopen("output.txt", "w", stdout);
    #endif
}





void solve(){
  ll n,a=-__LONG_LONG_MAX__,total=-__LONG_LONG_MAX__; cin>>n;
  ll arr[n];
  ll idx;
for(ll i=0; i<n; i++){
    cin>>arr[i];
    if(arr[i]>a){
        a=arr[i];
        idx=i;
    }
}
for(ll i =0; i<n; i++){
    if(i==idx) continue;
    else{
        if(arr[idx]*arr[i]+arr[idx]-arr[i]> total) total = arr[idx]*arr[i]+arr[idx]-arr[i];
    }
}

cout<<total<<'\n';

}

int main(){
    Fast_IO();
int t =1;
cin>>t;
while(t--){
solve();
}
return 0;
}