#include <iostream>
#include <vector>

using namespace std;

vector<int> copyElements(vector<int> array, vector<int> array2, int n, int i)
{

    if (n == array.size())
    {
        return array;
    }
    else
    {
        if (array[n] % 2 == 0)
        {
            array2[i] = array[n];
            i++;
        }

        return copyElements(array, array2, n + 1, i);
    }

}

int main()
{
    //initialize the two vectors
    vector<int> array;
    for(int i = 0; i < 8; i++)
    {
        array.push_back(i);
    }
    vector<int> array2;

    copyElements(array, array2, 0, 0);

    return 0;
}