Counting ones

#include <iostream>
#include <vector>
using namespace std;

int main() {
    int n;
    cin >> n;
    vector<unsigned long long> a(n);
    for (auto &x : a) cin >> x;
    int best = -1;
    unsigned long long bx = 0, by = 0;
    for (int i = 0; i < n; i++)
        for (int j = i + 1; j < n; j++) {
            int c = __builtin_popcountll(a[i] * a[j]);
            if (c > best) best = c, bx = a[i], by = a[j];
        }
    cout << best << "\n" << bx << " " << by << "\n";
}

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