using System;
using static System.Console;
using System.Linq;
using System.Collections.Generic;

class Program
{
    static int NN => int.Parse(ReadLine());
    static int[] NList => ReadLine().Split().Select(int.Parse).ToArray();
    static int[] LList(long n) => Enumerable.Repeat(0, (int)n).Select(_ => int.Parse(ReadLine())).ToArray();
    public static void Main()
    {
        Solve();
    }
    static void Solve()
    {
        var prime = Enumerable.Repeat(true, 10_000_002).ToArray();
        var list = new List<long>();
        for (var i = 2; i < prime.Length; ++i) if (prime[i])
        {
            if (i > 4 && prime[i - 2]) list.Add((long)i * (i - 2));
            for (var j = i * 2; j < prime.Length; j += i) prime[j] = false;
        }
        var t = NN;
        var ans = new long[t];
        for (var u = 0; u < t; ++u)
        {
            var n = long.Parse(ReadLine());
            var pos = LowerBound(0, n, list);
            if (pos == 0 && list[pos] > n) ans[u] = -1;
            else
            {
                if (pos == list.Count || list[pos] > n) --pos;
                ans[u] = list[pos];
            }
        }
        WriteLine(string.Join("\n", ans));
    }
    static int LowerBound(int left, long min, IList<long> list)
    {
        if (list[left] >= min) return left;
        var ng = left;
        var ok = list.Count;
        while (ok - ng > 1)
        {
            var center = (ng + ok) / 2;
            if (list[center] < min) ng = center;
            else ok = center;
        }
        return ok;
    }
}