/* 
 *      Author:    srtry
 *      Created:   2025-04-30T04:38:41+09:00
 */

use proconio::input;
use std::io::{stdout,Write,BufWriter};

fn solve(&n:&usize, twin_primes_prod:&Vec<usize>) -> Option<usize> {
    let mut left:usize = 0;
    let mut right:usize = twin_primes_prod.len()-1;
    let mut mid:usize = (left+right+1)/2;
    loop {
        if right-left <= 1 {
            break;
        }
        mid = (left+right+1)/2;
        if twin_primes_prod[mid] <= n {
            left = mid;
        } else {
            right = mid-1;
        }
    }

    if twin_primes_prod[right] <= n {
        return Some(twin_primes_prod[right])
    } else if twin_primes_prod[left] <= n {
        return Some(twin_primes_prod[left]);
    } else {
        return None;
    }
}

fn main() {
    let stdin = std::io::read_to_string(std::io::stdin()).unwrap();
    let mut stdin = stdin.split_whitespace();
    
    let mut max_max_p:usize = 0;
    let t:usize = stdin.next().unwrap().parse::<usize>().unwrap();
    let case = {
        let mut tmp:Vec<usize> = vec![0;t];
        for i in 0..t {
            tmp[i] = stdin.next().unwrap().parse::<usize>().unwrap();
            if tmp[i] > max_max_p {
                max_max_p = tmp[i];
            }
        }
        tmp
    };
    max_max_p = (max_max_p as f64).sqrt() as usize; 

    // エラトステネスの篩
    let mut is_prime:Vec<bool> = vec![true;max_max_p+3];
    is_prime[0] = false;
    is_prime[1] = false;
    for i in 2..is_prime.len() {
        if is_prime[i] {
            for j in i..=(max_max_p/i) {
                is_prime[j*i] = false;
            }
        }
    }

    // 双子素数の積
    let mut twin_primes_prod:Vec<usize> = Vec::new();
    for i in 0..=max_max_p {
        if is_prime[i] && is_prime[i+2] {
            twin_primes_prod.push(i*(i+2));
        }
    }

    
    let out = stdout();
    let mut out = BufWriter::new(out.lock());

    let mut ans;
    for &c in case.iter() {
        ans = solve(&c, &twin_primes_prod);
        match ans {
            Some(x) => write!(out, "{}\n", x).unwrap(),
            None => write!(out, "-1\n").unwrap(),
        }
    }
}