#include <bits/stdc++.h>

using namespace std;

#define For(i, a, n) for(int i =a;i<n;i++)
#define endl '\n'
#define vec vector

typedef long long ll;
typedef pair<ll, ll> pii;
template<typename... Args>
void dbg(Args&&... args){
    ((cerr<<args<<" |"),...);
    cerr<<endl;
}
template<class A, class B>
pair<A, B> operator+(const pair<A, B>&a, const pair<A, B>& b){
    return {a.first +b.first, a.second + b.second};
}
template<class A, class B>
ostream& operator<< (ostream& os, const pair<A, B>& a){
    return os<<"("<<a.first<<", "<<a.second<<")";
}
template<class A, class B, class C>
basic_ostream<A, B>& operator<<(basic_ostream<A, B>& os, const C&c){
    for(auto it=begin(c); it!=end(c);++it){
        os<<(it==begin(c)?"":" ")<<*it;
    }
    return os;
}
void solve(){
    int n, m;cin>>n>>m;
    ll sum = 0;
    ll male = 123124312312;
    For(i, 0, n){
        For(j, 0, m){
            ll a;cin>>a;
            sum += a;
            if((i+j)%2==1){
                male =min(male, a);
            }
        }
    }
    dbg(male);
    if(n%1||m%1)cout<<sum<<endl;
    else cout<<sum - male<<endl;
}

main(){
    cin.tie(0)->sync_with_stdio(0);
    cin.exceptions(cin.failbit);
    int t=1;//cin>>t;
    while(t--){
        solve();
    }
}