#include <bits/stdc++.h>

using namespace std;

#define rep(i, a, b) for (int i=a;i<(b); ++i)
#define all(x) begin(x), end(x)
#define sz(x) (int)(x).size()
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector <vi> vvi;

int main() {
    cin.tie(0)->sync_with_stdio(0);

    int N, M;
    cin >> N >> M;

    int sum = 0;
    int black = numeric_limits<int>::max();
    vvi G(N, vi(M));

    for(int i = 0; i < N; i++) {
        for(int j = 0; j < M; j++) {
            int curr;
            cin >> curr;
            G[i][j] = curr;
            sum += curr;
            if((i+j) % 2 == 1)
                black = min(black, curr);
        }
    }

    if(N % 2 == 0 and M % 2 == 0) {
        cout << sum - black << endl;
    }
    else
        cout << sum << endl;
}