#include <bits/stdc++.h>

using namespace std;
using ll = long long;

int arr[1000][1000];

int main() {
	ios::sync_with_stdio(0);
	cin.tie(0);

	int n, m;
	cin >> n >> m;

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

	if((n & 1) || (m & 1)) {
		cout << s << '\n';
		return 0;
	}

	ll mn = 10000000000ll;

	for(int i = 0; i < n; ++i) {
		for(int j = 0; j < m; ++j) {
			if((i+j) & 1) mn = min((ll)arr[i][j], mn);
		}
	}

	cout << s - mn << '\n';

	return 0;
}