#include <bits/stdc++.h>
#define ll long long
const ll con = 1e9;
#define YES cout << "YES\n"
#define NO cout << "NO\n"
#define Yes cout << "Yes\n"
#define No cout << "No\n"
using namespace std;
void solve() {
    int n , m ;
    cin >> n >> m;
    bool notiring = false ;
    ll grid[n][m];
    ll sumx = 0 ;
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < m; j++) {
            cin >> grid[i][j];
            sumx += grid[i][j];
        }
    }
    if ((n % 2== 0 && m % 2 !=0 ) || (n % 2 != 0 && m % 2 != 0)
        || (n % 2!= 0 && m % 2 ==0 ))
        notiring = true;
    if (notiring) {
        cout<<sumx<<'\n';
        return;
    }
    ll mini = INT_MAX ;
    for ( int i = 0 ; i < n ; i++) {
        for ( int j = 0 ; j < m ; j++) {
            if ( (i + j) % 2 != 0)
                mini = min(mini, grid[i][j]);
        }
    }
    cout << sumx - mini << '\n';
}
int main(){
    solve();
}