#define IOS ios_base::sync_with_stdio(0); cin.tie(0);

 #include <cstdio>//sprintf islower isupper

 #include <cstdlib>//malloc  exit strcat itoa system("cls")

 #include <iostream>//pair

 #include <fstream>//freopen("C:\\Users\\13606\\Desktop\\草稿.txt","r",stdin);

 #include <bitset>

 //#include <map>

 //#include<unordered_map>

 #include <vector>

 #include <stack>

 #include <set>

 #include <string.h>//strstr substr

 #include <string>

 #include <time.h>// srand(((unsigned)time(NULL))); Seed n=rand()%10 - 0~9;

 #include <cmath>

 #include <deque>

 #include <queue>//priority_queue<int, vector<int>, greater<int> > q;//less

 #include <vector>//emplace_back

 //#include <math.h>

 #include <cassert>

 //#include <windows.h>//reverse(a,a+len);// ~ ! ~ ! floor

 #include <algorithm>//sort + unique : sz=unique(b+1,b+n+1)-(b+1);+nth_element(first, nth, last, compare)

 using namespace std;//next_permutation(a+1,a+1+n);//prev_permutation

 //******************

 int abss(int a);

 int lowbit(int n);

 int Del_bit_1(int n);

 int maxx(int a,int b);

 int minn(int a,int b);

 double fabss(double a);

 void swapp(int &a,int &b);

 clock_t __STRAT,__END;

 double __TOTALTIME;

 void _MS(){__STRAT=clock();}

 void _ME(){__END=clock();__TOTALTIME=(double)(__END-__STRAT)/CLOCKS_PER_SEC;cout<<"Time: "<<__TOTALTIME<<" s"<<endl;}

 //***********************

 #define rint register int

 #define fo(a,b,c) for(rint a=b;a<=c;++a)

 #define fr(a,b,c) for(rint a=b;a>=c;--a)

 #define mem(a,b) memset(a,b,sizeof(a))

 #define pr printf

 #define sc scanf

 #define ls rt<<1

 #define rs rt<<1|1

 typedef vector<int> VI;

 typedef long long ll;

 const double E=2.718281828;

 const double PI=acos(-1.0);

 //const ll INF=(1LL<<60);

 const int inf=(<<);

 const double ESP=1e-;

 const int mod=(int)1e9+;

 const int N=;

 const int M=5e5+;

 class DINIC

 {

 public:

 //    const int MAXN=10004,MAXWAY=100005;

     int n,way,max_flow,deep[N];

     int tot,head[N],cur[N];

     struct EDGE{

         int to,next;

         int dis;

     }edge[M];

     void Init(int n_)

     {

         tot=-;//因为加反向边要^1,所以要从0开始;

         n=n_;

         max_flow=;

         for(int i=;i<=n_;++i)

             head[i]=-;

     }

     void add(int from,int to,int V)

     {

         //正向

         ++tot;

         edge[tot].to=to;

         edge[tot].dis=V;

         edge[tot].next=head[from];

         head[from]=tot;

         //反向

         swap(from,to);

         ++tot;

         edge[tot].to=to;

         edge[tot].dis=;

         edge[tot].next=head[from];

         head[from]=tot;

     }

     queue<int>q;

     bool bfs(int s,int t)

     {

         for(int i=;i<=n;++i)

             deep[i]=inf;

         while(!q.empty())q.pop();

         for(int i=;i<=n;++i)cur[i]=head[i];

         deep[s]=;

         q.push(s);

         while(!q.empty())

         {

             int now=q.front();q.pop();

             for(int i=head[now];i!=-;i=edge[i].next)

             {

                 if(deep[edge[i].to]==inf&&edge[i].dis)

                 {

                     deep[edge[i].to]=deep[now]+;

                     q.push(edge[i].to);

                 }

             }

         }

         return deep[t]<inf;

     }

     int dfs(int now,int t,int limit)

     {

         if(!limit||now==t)return limit;

         int flow=,f;

         for(int i=cur[now];i!=-;i=edge[i].next)

         {

             cur[now]=i;

             if(deep[edge[i].to]==deep[now]+&&(f=dfs(edge[i].to,t,min(limit,edge[i].dis))))

             {

                 flow+=f;

                 limit-=f;

                 edge[i].dis-=f;

                 edge[i^].dis+=f;

                 if(!limit)break;

             }

         }

         return flow;

     }

     void Dinic(int s,int t)

     {

         while(bfs(s,t))

             max_flow+=dfs(s,t,inf);

     }

 }G;

 int a[N][N],color[N][N];

 int main()

 {

     int n,m;

     while(~sc("%d%d",&n,&m))

     {

         ll TOT=;

         for(int i=;i<=n;++i)

             for(int j=;j<=m;++j)

                 sc("%d",&a[i][j]),TOT+=a[i][j];

         G.Init(n*m+);

         int S=n*m+,T=n*m+,cnt=;

         for(int i=;i<=n;++i)

         {

             for(int j=;j<=m;++j)

             {

                 if(i&)

                 {

                     if(j&)

                         color[i][j]=;

                     else

                         color[i][j]=;

                 }

                 else

                 {

                     if(j&)

                         color[i][j]=;

                     else

                         color[i][j]=;

                 }

             }

         }

         for(int i=;i<=n;++i)

         {

             for(int j=;j<=m;++j)

             {

                 ++cnt;

                 if(color[i][j]==)

                 {

                     G.add(S,cnt,a[i][j]);

                     if(i>)G.add(cnt,cnt-m,inf);

                     if(j>)G.add(cnt,cnt-,inf);

                     if(i<n)G.add(cnt,cnt+m,inf);

                     if(j<m)G.add(cnt,cnt+,inf);

                 }

                 else

                     G.add(cnt,T,a[i][j]);

             }

         }

     /*    fo(i,1,n)

         {

             fo(j,1,m)

                 pr("%d ",color[i][j]);

             pr("\n");

         }*/

         G.Dinic(S,T);

         pr("%lld\n",TOT-G.max_flow);

     }

     return ;

 }

 /**************************************************************************************/

 int maxx(int a,int b)

 {

     return a>b?a:b;

 }

 void swapp(int &a,int &b)

 {

     a^=b^=a^=b;

 }

 int lowbit(int n)

 {

     return n&(-n);

 }

 int Del_bit_1(int n)

 {

     return n&(n-);

 }

 int abss(int a)

 {

     return a>?a:-a;

 }

 double fabss(double a)

 {

     return a>?a:-a;

 }

 int minn(int a,int b)

 {

     return a<b?a:b;

 }