31. Find EVENS in dual array C++

#include <iostream>
#include <vector>

int main()
{
    using namespace std;

    int row_number, col_number;
    cin >> row_number >> col_number;

    vector<vector<int>> matrix;
    for (int row = 0; row < row_number; ++row)
    {
        vector<int> matrix_row;
        for (int col = 0; col < col_number; ++col)
        {
            int n;
            cin >> n;
            matrix_row.push_back(n);
        }
        matrix.push_back(matrix_row);
    }

    int even_count = 0;
    for (int row = 0; row < row_number; ++row)
    {
        for (int col = 0; col < col_number; ++col)
        {
            if (matrix[row][col] % 2 == 0)
                ++even_count;
        }
    }

    cout << even_count << endl;

    return 0;
}

//#include <iostream>
//#include <vector>
//int main()
//{
//  using namespace std;
//
//  int rows, cols;
//  cin >> rows >> cols;
//
//  vector<int> matrix;
//  int even_count = 0;
//  for (int i = 0; i < rows * cols; ++i)
//  {
//      int n;
//      cin >> n;
//      matrix.push_back(n);
//      if (!(n & 1))
//          ++even_count;
//  }
//
//  cout << even_count << endl;
//
//  return 0;
//}