#include<cstdio>

#include<cmath>

#include<cstring>

#include<algorithm>

using namespace std;

const int N=;

int num,k,dis[N],t,ans,q[N],fi[N],ne[N],ans1,zz[N],sl[N],n,m,a[][];

void jb(int x,int y,int z)

{

    ne[num]=fi[x];

    fi[x]=num;

    zz[num]=y;

    sl[num++]=z;

    swap(x,y);

    z=;

    ne[num]=fi[x];

    fi[x]=num;

    zz[num]=y;

    sl[num++]=z;

}

int bfs()

{

    memset(dis,0xff,sizeof dis);

    dis[]=;

    int l=,r=;

    q[]=;

    while (l<r)

     {

         int j=q[++l];

         for (int i=fi[j];i!=-;i=ne[i])

          if (dis[zz[i]]<&&sl[i]>)

           {

               dis[zz[i]]=dis[j]+;

               q[++r]=zz[i];

           }

     }

    if (dis[n]>)return ;

    return ;

}

int find(int x,int low)

{

    int b=;

    if (x==n)return low;

    for (int i=fi[x];i!=-;i=ne[i])

     if (sl[i]>&&dis[zz[i]]==dis[x]+&&(b=find(zz[i],min(low,sl[i]))))

      {

          sl[i]-=b;

          sl[i^]+=b;

          return b;

      }

    return ;

}

void doit()

{

    memset(fi,-,sizeof fi);

    memset(a,,sizeof a);

    memset(sl,,sizeof sl);

    ans1=ans=;num=;

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

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

      {

          scanf("%d",&a[i][j]);

          ans1+=a[i][j];

          if ((i+j)&)jb(,(i-)*m+j+,a[i][j]);

          else jb((i-)*m+j+,n*m+,a[i][j]);

      }

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

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

      if ((i+j)&)

       {

           if (i!=)jb((i-)*m+j+,(i-)*m+j+,1e9);

           if (i!=n)jb((i-)*m+j+,i*m+j+,1e9);

           if (j!=)jb((i-)*m+j+,(i-)*m+j,1e9);

           if (j!=m)jb((i-)*m+j+,(i-)*m+j+,1e9);

       }

    int t;ans=;

    n=n*m+;

    while (bfs())

     while (t=find(,1e9))ans+=t;

    printf("%d\n",ans1-ans);

}

int main()

{

    while (~scanf("%d%d",&n,&m))doit();

}