#include <algorithm>
#include <climits>
#include <cstdio>
#include <cstring>
#include <queue>
using namespace std;
const int MAXN=10010,MAXM=59610;
int m,n,S,T,cnt,ans,head[MAXN],cur[MAXN],dis[MAXN];
struct edge
{
    int nxt,to,w;
}e[MAXM];
void AddEdge(int x,int y,int w)
{
    e[++cnt].nxt=head[x];
    e[cnt].to=y;
    e[cnt].w=w;
    head[x]=cnt;
}
void AddEdges(int x,int y,int w)
{
    AddEdge(x,y,w);
    AddEdge(y,x,0);
}
int num(int i,int j)
{
    return (i-1)*n+j;
}
void Init(int i,int j)
{
    int w,t=num(i,j);
    scanf("%d",&w);
    ans+=w;
    if(i+j&1)
        AddEdges(t,T,w);
    else
    {
        AddEdges(S,t,w);
        if(i>1)
            AddEdges(t,t-n,INT_MAX);
        if(i<m)
            AddEdges(t,t+n,INT_MAX);
        if(j>1)
            AddEdges(t,t-1,INT_MAX);
        if(j<n)
            AddEdges(t,t+1,INT_MAX);
    }
}
bool BFS(void)
{
    queue<int> q;
    memset(dis,0,sizeof dis);
    q.push(S);
    dis[S]=1;
    while(!q.empty())
    {
        int x=q.front();
        q.pop();
        for(int i=head[x],t;i;i=e[i].nxt)
            if(e[i].w && !dis[t=e[i].to])
            {
                q.push(t);
                dis[t]=dis[x]+1;
            }
    }
    return dis[T];
}
int DFS(int x,int k)
{
    if(x==T || !k)
        return k;
    int tmp=0;
    for(int i=cur[x],t,flow;i;i=e[i].nxt)
        if(e[i].w && dis[t=e[i].to]==dis[x]+1 && (flow=DFS(t,min(k,e[i].w))))
        {
            cur[x]=i;
            e[i].w-=flow;
            e[((i-1)^1)+1].w+=flow;
            k-=flow;
            tmp+=flow;
        }
    if(!tmp)
        dis[x]=0;
    return tmp;
}
void Dinic(void)
{
    int flow;
    while(BFS())
        while(memcpy(cur,head,sizeof cur),flow=DFS(S,INT_MAX))
            ans-=flow;
}
int main(int argc,char *argv[])
{
    scanf("%d %d",&m,&n);
    T=m*n+1;
    for(int i=1;i<=m;++i)
        for(int j=1;j<=n;++j)
            Init(i,j);
    Dinic();
    printf("%d",ans);
    return 0;
}