#include <iostream>

void simple(int r, int c)
{
    // std::cerr << "simple\n";
    long long sum = 0;
    int tmp;
    for (size_t i = 0; i < r * c; i++)
    {
        std::cin >> tmp;
        sum += tmp;
        // std::cerr << tmp << "\n";
    }
    
    std::cout << sum << "\n";
}

void not_so_simple(int r, int c)
{
    // std::cerr << "not_so_simple\n";

    long long sum = 0;
    int tmp;
    int min_el = 1e9;

    for (size_t i = 0; i < r * c; i++)
    {
        std::cin >> tmp;
        sum += tmp;
        if (i % 2 == 1 && tmp < min_el)
        {
            min_el = tmp;
        }
    }
    sum -= min_el;
    
    std::cout << sum << "\n";
}

int main(int argc, char const *argv[])
{
    int r, c;
    std::cin >> r >> c;

    if (r % 2 == 1 || c % 2 == 1)
    {
        simple(r, c);
    }
    else
    {
        not_so_simple(r, c);
    }
        



    return 0;
}