num27.8

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

int main()
{
    ifstream input("C:\\Users\\Максим\\Downloads\\28128_A (4).txt");
    long long int n = 0, now = 0, max1 = 0, max2 = 0, max01 = 0, max02 = 0, s = 0;
    input >> n;
    for (size_t i = 0; i < n; i++)
    {
        input >> now;
        if (now % 3 == 0 && now > max01) {
            if (max01 > max02)
                max02 = max01;
            max01 = now;
        }
        else if (now % 3 == 0 && now > max02) {
            max02 = now;
        }
        if (now % 3 == 1 && now > max1) {
            max1 = now;
        }
        if (now % 3 == 2 && now > max2) {
            max2 = now;
        }
    }
    cout << max(max01 + max02, max2 + max1);
}