Omenat

#include <iostream>
#include <vector>
#include <set>
#include <algorithm>

using namespace std;

int main() {
    cin.sync_with_stdio(false);
    cin.tie(0);

    long n;
    cin >> n;
    long summa = 0;
    bool mod1 = false;
    bool mod2 = false;

    for (long i = 0; i < n; i++) {
        long o;
        cin >> o;

        summa += o;
        if (o % 3 == 1) {
            mod1 = true;
        } else if (o % 3 == 2) {
            mod2 = true;
        }
    }

    if (summa % 3 == 0) {
        cout << n << "\n";
    } else {
        if ((summa % 3 == 1 and mod1) or (summa % 3 == 2 and mod2)) {
            cout << n - 1;
        } else {
            cout << n - 2;
        }
        cout << "\n";
    }

    return 0;
}

Test 1

Group: 1

Verdict: ACCEPTED

Test 2

Group: 1

Verdict: ACCEPTED

Test 3

Group: 1

Verdict: ACCEPTED

Test 4

Group: 1

Verdict: ACCEPTED

Test 5

Group: 1

Verdict: ACCEPTED

Test 6

Group: 1

Verdict: ACCEPTED

Test 7

Group: 2

Verdict: ACCEPTED

Test 8

Group: 2

Verdict: ACCEPTED

Test 9

Group: 2

Verdict: ACCEPTED

Test 10

Group: 2

Verdict: ACCEPTED

Test 11

Group: 2

Verdict: ACCEPTED

Test 12

Group: 2

Verdict: ACCEPTED

Test 13

Group: 3

Verdict: ACCEPTED

Test 14

Group: 3

Verdict: ACCEPTED

Test 15

Group: 3

Verdict: ACCEPTED

Test 16

Group: 3

Verdict: ACCEPTED

Test 17

Group: 3

Verdict: ACCEPTED

Test 18

Group: 3

Verdict: ACCEPTED