CCC 2019 S2 Pretty Average Primes

    1#include <bits/stdc++.h>
    2using namespace std;
    3using ll = long long;
    4const int inf = 1e9;
    5const long long INF = 1e17; //❄️
    6int main() {
    7    ios::sync_with_stdio(0); cin.tie(0);
    8    auto prime = [&] (int x) {
    9    if (x == 2) return true;
    10    if (x < 2 || !(x & 1)) return false;
    11    for (int i = 3; i * i <= x; i += 2) {
    12        if (x % i == 0) return false;
    13    }
    14    return true;
    15};
    16    int t; cin >> t;
    17    while (t--) {
    18        int n; cin >> n;
    19        n *= 2;
    20        for (int i = 3; i <= n / 2; i += 2) {
    21            int x = n - i;
    22            if (prime(i) && prime(x)) {
    23                cout << i << " " << x << '\n';
    24                break;
    25            }
    26        }
    27    }
    28    return 0;
    29}