#include <bits/stdc++.h>

using namespace std;

typedef long long int ll;
typedef double ld;
typedef pair<ll,ll> ii;
typedef vector <ll> vi;
typedef vector <ii> vii;
#define PB push_back
#define ff first
#define ss second
#define MP make_pair
#define FOR(p,a,b) for( ll p = (a); p < (ll)(b); ++p)
#define F(a) FOR(i,0,a)
#define FF(a) FOR(j,0,a)
#define EPS (1e-10)
#define EQ(a,b) (fabs(a-b) <= fabs(a+b)*EPS)

int main() {

    ll n, m, tmp, sum = 0, min = 1000;
    scanf(" %lld %lld",&n,&m);
    F(n) FF(m) {
        scanf(" %lld",&tmp);
        sum += tmp;
        if(tmp<min && ((i+j)%2)) min = tmp;
    }
    if(n%2==0 && m%2==0) sum -= min;
    printf("%lld\n",sum);
   

    return 0;
}