#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef double ld;

int main()
{
    int n, m;
    cin >> n >> m;

    vector<vector<int>> p(n, vector<int>(m));

    for (int i = 0; i < n; i++)
    {
        for (int j = 0; j < m; j++)
        {
            cin >> p[i][j];
        }
    }

    ll ans = 0;
    for (int i = 0; i < n; i++)
    {
        for (int j = 0; j < m; j++)
        {
            ans += p[i][j];
        }
    }
    if ((n % 2 == 1) or (m % 2 == 1))
    {
        cout << ans << endl;
    }
    else
    {
        int mini = 99999999;

        for (int i = 0; i < n; i++)
        {
            for (int j = (i % 2) + 1; j < m; j += 2)
            {
                if (mini > p[i][j])
                    mini = p[i][j];
            }
        }
        cout << ans - mini << endl;
    }

    return 0;
}