#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

int main(){
    int t, n, tp, i, j;
    vector<int> a;
    long long ans;

    cin >> t;

    for (i=0; i<t; i++){
        cin >> n;
        a.clear();

        for(j=0; j<n; j++){
            cin >> tp;
            a.push_back(tp);
        }

        sort(a.begin(), a.end());
        if (find(a.begin(), a.end(), 0) != a.end()) ans = 0LL;
        else{
            ans = (long long) a.front() * a.back();
            if (ans < 0){
                auto it = upper_bound(a.begin(), a.end(), 0);
                ans = (long long) *it * *(it -1);
            }
        }

        cout << ans << "\n";

    }

    return 0;
}