#include <iostream>
#include <algorithm>
#include <vector>
#include <set>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using ll = long long; 
using mint = modint998244353;
using vi = vector<int>;
using vvi = vector<vi>;
using vvvi = vector<vvi>;
using vll = vector<ll>;
using vvll = vector<vll>;
using vvvll = vector<vvll>;
using vmi = vector<mint>;
using vvmi = vector<vmi>;
using vvvmi = vector<vvmi>;
#define all(a) (a).begin(), (a).end()
#define rep2(i, m, n) for (int i = (m); i < (n); ++i)
#define rep(i, n) rep2(i, 0, n)
#define drep2(i, m, n) for (int i = (m)-1; i >= (n); --i)
#define drep(i, n) drep2(i, n, 0)

class Primes{
    private:
        int size_p;
        vector<bool> is_p;
        vector<int> primes;
        vector<int> minfactor;
        vector<int> mobius;
        void eratos(int n){
            for(int i=2; i<=n; i++){
                if(minfactor[i] < i)continue;
                primes.emplace_back(i);
                mobius[i] = -1;
                is_p[i] =true;
                for(int j = 2*i; j<=n; j+=i){
                    minfactor[j] = min(i, minfactor[j]);
                    mobius[j] = ((j/i) % i == 0) ? 0 : -mobius[j];
                }
            }
        }
        
    public:
        Primes(int n){
            size_p = n;
            rep(i, size_p+1)is_p.emplace_back(false);
            rep(i, size_p+1)minfactor.emplace_back(i);
            rep(i, size_p+1)mobius.push_back(1);
            mobius[1] = 1;
            eratos(size_p);
            
        }

        bool isprime(int n){
            return is_p[n];
        }
        vector<int> listPrimes(){
            return primes;
        }
        int getMobius(int n){return mobius[n];}

};



int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    Primes pr = Primes(10000010);
    vll prd;
    vi v = pr.listPrimes();
    for(auto p : v){
        if(pr.isprime(p+2)){
            prd.push_back((ll)p*(ll)(p+2));
        }
    }
    int t; cin >> t;
    while(t--){
        ll n; cin >> n;
        if(n < 15){
            cout << -1 << endl;
        }else{
            cout << *(--upper_bound(all(prd), n)) << endl;
        }
    }


    return 0;
}