#include <bits/stdc++.h>

using namespace std;

#define ll long long 

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


    int minm = INT32_MAX;
    ll total = 0;

    for (int i = 0; i < n; i++)
    {
        for(int j = 0; j<m; j++){
            int val; cin>>val;
            total+=val;
            if((i+j)%2==1)
                minm = min(minm, val);
        }
    }
    
    if((n&1) ||(m&1))
        cout<<total<<'\n';
    else
        cout<<total-minm<<'\n';
}