#include <bits/stdc++.h>
#include <atcoder/all>
#include <boost/multiprecision/cpp_dec_float.hpp>
#include <boost/multiprecision/cpp_int.hpp>
namespace mp = boost::multiprecision;
using Bint = mp::cpp_int;
using namespace std;
using namespace atcoder;
#define rep(i, n) for(int i=0;i<(n);++i)
#define rep1(i, n) for(int i=1;i<=(n);i++)
#define ll long long
using mint = modint998244353;
using P = pair<ll,ll>;
using lb = long double;
using T = tuple<ll, ll, ll>;
#ifdef LOCAL
#  include <debug_print.hpp>
#  define dbg(...) debug_print::multi_print(#__VA_ARGS__, __VA_ARGS__)
#else
#  define dbg(...) (static_cast<void>(0))
#endif

int main()
{
    int t;
    cin >> t;
    vector<ll> ps;
    vector<bool> used(1e7+1);
    for(int i=2;i<=1e7;i++) {
        if(used[i]) continue;
        ps.push_back(i);
        for(int j=i+i;j<=1e7;j+=i) {
            used[j] = 1;
        }
    }
    vector<ll> p;
    for(int i=0;i<ps.size()-1;i++) {
        if(ps[i+1]-ps[i]==2) p.push_back(ps[i]*ps[i+1]);
    }
    dbg(p);
    while(t--) {
        ll n;
        cin >> n;
        auto it = upper_bound(p.begin(),p.end(),n);
        if(it==p.begin()) {
            cout << -1 << endl;
        }
        else{
            it--;
            cout << *it << endl;
        }
    }
    return 0;
}