Counting ones

#include <bits/stdc++.h>

using namespace std;

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);

    int n;
    if (!(cin >> n)) return 0;

    vector<long long> a(n);
    for (int i = 0; i < n; ++i) {
        cin >> a[i];
    }

    int max_popcount = -1;
    long long best_a = -1, best_b = -1;

    for (int i = 0; i < n; ++i) {
        for (int j = i + 1; j < n; ++j) {
            long long prod = a[i] * a[j];
            int current_popcount = __builtin_popcountll(prod);

            if (current_popcount > max_popcount) {
                max_popcount = current_popcount;
                best_a = a[i];
                best_b = a[j];
            }
        }
    }

    cout << max_popcount << "\n";
    cout << best_a << " " << best_b << "\n";

    return 0;
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED