#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<cmath>
#include<queue>
#define ll long long
#define inf 50000000
#define re register
#define id m*(i-1)+j
using namespace std;
struct po
{int from,to,dis,nxt;
}edge[1000001];
int head[1000001],cur[1000001],dep[60001],n,m,s,t,u,num=-1,x,y,l,tot,sum,d;
int nm,a[120][120];
int dx[5]={0,1,0,-1,0};
int dy[5]={0,0,1,0,-1};
inline int read()
{int x=0,c=1;char ch=' ';while((ch>'9'||ch<'0')&&ch!='-')ch=getchar();while(ch=='-')c*=-1,ch=getchar();while(ch<='9'&&ch>='0')x=x*10+ch-'0',ch=getchar();return x*c;
}
inline void add_edge(int from,int to,int dis)
{edge[++num].nxt=head[from];edge[num].from=from;edge[num].to=to;edge[num].dis=dis;head[from]=num;
}
inline void add(int from,int to,int dis)
{add_edge(from,to,dis);add_edge(to,from,0);
}
inline bool bfs()
{memset(dep,0,sizeof(dep));queue<int> q;while(!q.empty())q.pop();dep[s]=1;q.push(s);while(!q.empty()){int now=q.front();q.pop();for(re int i=head[now];i!=-1;i=edge[i].nxt){int v=edge[i].to;if(dep[v]==0&&edge[i].dis>0){dep[v]=dep[now]+1;if(v==t)return 1;q.push(v); }}}return 0;
}
inline int dfs(int u,int dis)
{if(u==t)return dis;int diss=0;for(re int i=head[u];i!=-1;i=edge[i].nxt){int v=edge[i].to;if(dep[v]==dep[u]+1&&edge[i].dis!=0){int check=dfs(v,min(dis,edge[i].dis));if(check>0){diss+=check;dis-=check;edge[i].dis-=check;edge[i^1].dis+=check;if(dis==0) break;}}}return diss;
}
inline int dinic()
{int ans=0;while(bfs()){for(re int i=0;i<=t;i++)cur[i]=head[i];while(int d=dfs(s,inf))ans+=d;}return ans;
}
int main()
{memset(head,-1,sizeof(head));n=read();m=read();s=0;t=n*m+1;for(re int i=1;i<=n;i++)for(re int j=1;j<=m;j++)a[i][j]=read(),sum+=a[i][j];for(re int i=1;i<=n;i++)for(re int j=1;j<=m;j++){if((i+j)%2==0)add(s,id,a[i][j]);elseadd(id,t,a[i][j]);for(re int h=1;h<=4;h++){int lx=i+dx[h],ly=j+dy[h];if(lx>=1&&lx<=n&&ly>=1&&ly<=m)if((lx+ly)%2!=0)add(id,(lx-1)*m+ly,inf);}}cout<<sum-dinic();
}