#include<cstdio>

 #include<cstdlib>

 #include<cmath>

 #include<cstring>

 #include<algorithm>

 #include<iostream>

 #include<vector>

 #include<map>

 #include<set>

 #include<queue>

 #include<string>

 #define inf 1000000000

 #define maxn 10000+5

 #define maxm 100000+5

 #define eps 1e-10

 #define ll long long

 #define pa pair<int,int>

 #define for0(i,n) for(int i=0;i<=(n);i++)

 #define for1(i,n) for(int i=1;i<=(n);i++)

 #define for2(i,x,y) for(int i=(x);i<=(y);i++)

 #define for3(i,x,y) for(int i=(x);i>=(y);i--)

 #define mod 1000000007

 using namespace std;

 inline int read()

 {

     int x=,f=;char ch=getchar();

     while(ch<''||ch>''){if(ch=='-')f=-;ch=getchar();}

     while(ch>=''&&ch<=''){x=*x+ch-'';ch=getchar();}

     return x*f;

 }

 int  n,m,s,t,ans,tot=,head[maxn],cur[maxn],h[maxn],q[maxn],num[][];

 struct edge{int go,next,v;}e[maxm];

 const int dx[]={,,-,};

 const int dy[]={,,,-};

 void ins(int x,int y,int z){e[++tot].go=y;e[tot].v=z;e[tot].next=head[x];head[x]=tot;}

 void insert(int x,int y,int z){ins(x,y,z);ins(y,x,);}

 bool bfs()

 {

     for(int i=s;i<=t;i++)h[i]=-;

     int l=,r=;q[]=s;h[s]=;

     while(l<r)

     {

         int x=q[++l];

         for(int i=head[x];i;i=e[i].next)

          if(e[i].v&&h[e[i].go]==-)

          {

             h[e[i].go]=h[x]+;q[++r]=e[i].go;

          }

     }

     return h[t]!=-;

 }

 int dfs(int x,int f)

 {

     if(x==t) return f;

     int tmp,used=;

     for(int i=cur[x];i;i=e[i].next)

      if(e[i].v&&h[e[i].go]==h[x]+)

     {

         tmp=dfs(e[i].go,min(e[i].v,f-used));

         e[i].v-=tmp;if(e[i].v)cur[x]=i;

         e[i^].v+=tmp;used+=tmp;

         if(used==f)return f;       

     }

     if(!used) h[x]=-;

     return used;

 }

 void dinic()

 {

     while(bfs())

     {

         for (int i=s;i<=t;i++)cur[i]=head[i];ans-=dfs(s,inf);

     }

 }

 int main()

 {

     freopen("input.txt","r",stdin);

     freopen("output.txt","w",stdout);

     n=read();m=read();s=;t=n*m+;

     for1(i,n)for1(j,m)

     {

         int x=read();

         num[i][j]=(i-)*m+j;ans+=x;

         if((i+j)&)insert(s,num[i][j],x);else insert(num[i][j],t,x);

     }

     for1(i,n)for1(j,m)if((i+j)&)

         for0(k,)

         {

             int x=i+dx[k],y=j+dy[k];

             if(x<||x>n||y<||y>m)continue;

             insert(num[i][j],num[x][y],inf);

         }

     dinic();

     printf("%d\n",ans);

     return ;

 }