#include <stdio.h>
#include <atcoder/all>
#include <bits/stdc++.h>
using namespace std;
using namespace atcoder;
using mint = modint998244353;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf32 1000000001
#define Inf64 4000000000000000001LL

int main(){
	
	vector f(10000001,true);
	f[0] = false,f[1] = false;

	for(int i=2;i<f.size();i++){
		if(f[i]){
			for(int j=2*i;j<f.size();j+=i){
				f[j] = false;
			}
		}
	}
	vector<long long> vs;
	rep(i,f.size()-2){
		if(f[i] && f[i+2]){
			vs.push_back((long long)i * (i+2));
		}
	}
	int _t;
	cin>>_t;
	rep(_,_t){
		long long n;
		cin>>n;
		auto it = upper_bound(vs.begin(),vs.end(),n);
		if(it== vs.begin()){
			cout<<-1<<endl;
		}
		else{
			it--;
			cout<<*it<<endl;
		}
	}
	return 0;
}