#ifdef NACHIA
#define _GLIBCXX_DEBUG
#else
#define NDEBUG
#endif
#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <map>
using i64 = long long;
using u64 = unsigned long long;
#define rep(i,n) for(i64 i=0; i<i64(n); i++)
const i64 INF = 1001001001001001001;
template<typename A> void chmin(A& l, const A& r){ if(r < l) l = r; }
template<typename A> void chmax(A& l, const A& r){ if(l < r) l = r; }
using namespace std;




void testcase(){
    i64 Z = 10000000;
    vector<int> sieve(Z+1, 1);
    sieve[0] = sieve[1] = 0;
    for(i64 p=2; p*p<=Z; p++) if(sieve[p]) for(i64 q=p*p; q<=Z; q+=p) sieve[q] = 0;
    vector<i64> T;
    rep(i,Z-1) if(sieve[i] && sieve[i+2]) T.push_back(i * (i+2));
    i64 Q; cin >> Q;
    rep(t,Q){
        i64 N; cin >> N;
        i64 p = upper_bound(T.begin(), T.end(), N) - T.begin();
        if(p == 0){
            cout << "-1\n";
        } else {
            cout << T[p-1] << "\n";
        }
    }
}

int main(){
    ios::sync_with_stdio(false); cin.tie(nullptr);
    testcase();
    return 0;
}