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

using namespace std;

int main()
{
    int siz = 1e7;
    vector<int> isp(siz + 1);
    isp[0] = isp[1] = 1;
    for (int i = 2; i <= siz; ++i)
    {
        if (isp[i]) continue;
        for (int j = 2; i * j <= siz; ++j) isp[i * j] = 1;
    }
    vector<long long> v;
    for (int i = 2; i < siz - 1; ++i)
    {
        if (isp[i] | isp[i + 2]) continue;
        v.push_back((long long)i * (i + 2));
    }
    int t;
    cin >> t;
    while (t--)
    {
        long long n;
        cin >> n;
        auto itr = upper_bound(v.begin(), v.end(), n);
        if (itr == v.begin()) cout << -1 << endl;
        else cout << *(--itr) << endl;
    }
}