#include <bits/stdc++.h>
using namespace std;
using ll = long long;

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    int T;
    cin >> T;
    while(T--){
        int n;
        cin >> n;
        vector<ll> a, b;
        for(int i = 0; i < n; i++){
            ll v;
            cin >> v;
            if(v >= 0) a.emplace_back(v);
            else b.emplace_back(v);
        }
        sort(a.begin(), a.end());
        sort(b.begin(), b.end());
        if(!a.empty() && !b.empty()){
            cout << a[0] * b.back() << '\n';
            continue;
        }
        ll ans = 1ll << 60;
        for(int i = 0; i < a.size(); i++){
            ans = min(ans, a.back() * a[i]);
        }
        for(int i = 0; i < b.size(); i++){
            ans = max(ans, b[i] * b[0]);
        }
        cout << ans << '\n';
    }
}