#include <bits/stdc++.h>
using namespace std;

#define ALL(x) (x).begin(),(x).end()
#define IO ios::sync_with_stdio(false),cin.tie(nullptr);
#define LB(v, x) (ll)(lower_bound(ALL(v),x)-(v).begin())
#define UQ(v) sort(ALL(v)),(v).erase(unique(ALL(v)),v.end())
#define REP(i, n) for(ll i=0; i<(ll)(n); i++)
#define FOR(i, a, b) for(ll i=(ll)(a); (a)<(b) ? i<(b) : i>(b); i+=((a)<(b) ? 1 : -1))
#define chmax(a, b) ((a)<(b) ? ((a)=(b), 1) : 0)
#define chmin(a, b) ((a)>(b) ? ((a)=(b), 1) : 0)

template<typename T> using rpriority_queue=priority_queue<T,vector<T>,greater<T>>;
using ll=long long; const int INF=1e9+10; const ll INFL=4e18; using ld=long double; using ull=uint64_t;
using VI=vector<int>; using VVI=vector<VI>; using VL=vector<ll>; using VVL=vector<VL>;
using PL=pair<ll,ll>; using VP=vector<PL>; using WG=vector<vector<pair<int,ll>>>;


//----------------------------------------------------------

int main() {
    IO; int T; cin>>T;

    const int mx=1e7;
    vector<bool> isp(mx+1,true);
    isp[0]=isp[1]=false;
    FOR(i,2,mx+1) if(isp[i]) for(int j=i*2; j<=mx; j+=i) isp[j]=false;

    VL ans;
    for(int i=3; i+2<=mx; i+=2) if(isp[i]&isp[i+2]) ans.push_back((ll)i*(i+2));

    while(T--) {
        ll N; cin>>N;

        int idx=LB(ans,N+1)-1;

        if(0<=idx&&idx<ans.size()) cout<<ans[idx]<<'\n';
        else cout<<-1<<'\n';
    }
}