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

int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    int T; cin >> T;
    while(T--){
        int N; cin >> N;
        vector<long long> plus,minus;
        bool zero = false;
        while(N--){
            int a; cin >> a;
            if(a == 0) zero = true;
            else if(a > 0) plus.push_back(a);
            else minus.push_back(a);
        }
        if(zero) cout << "0\n";
        else{
            if(plus.size() && minus.size()) cout << *min_element(plus.begin(),plus.end())*(*max_element(minus.begin(),minus.end())) << "\n";
            else{
                if(plus.size() == 0) swap(plus,minus);
                cout << *min_element(plus.begin(),plus.end())*(*max_element(plus.begin(),plus.end())) << "\n";
            }
        }
    }
}