#include <iostream>
using namespace std;

/* compile hamster.cpp && ./hamster < hamsterfiles/1.in*/
/* compile hamster.cpp && ./hamster < hamsterfiles/2.in*/

int main () {
    int N, M; /* size of hamster maze */
    int sum = 0;
    int min_val = 1001;

    cin >> N >> M;

    int maze[N][M];

    for (int i = 0; i < N; i++) {
        for (int j = 0; j < M; j++) {
            cin>>maze[i][j];
            sum += maze[i][j];
            /*!(i == 0 && j == 0) && !(i == N-1 && j == M-1)*/
            if(maze[i][j] < min_val && (i+j) % 2 ==1) {
                min_val = maze[i][j];       
            }
        }   
    }

    if(M % 2 == 1 || N % 2 == 1) {
        cout << sum;
        return 0;
    }

    sum -= min_val;
    cout << sum;
    return 0;
}