#include<iostream>
#include<cstdio>
#include<cstring>
#include<queue>
#include<algorithm>
#define LL long long int
using namespace std;
const int maxn=100005,maxm=10000005,INF=2000000000;inline int read(){int out=0,flag=1;char c=getchar();while(c<48||c>57) {if(c=='-') flag=-1;c=getchar();}while(c>=48&&c<=57) {out=out*10+c-48;c=getchar();}return out*flag;
}int head[maxn],nedge=0;
struct EDGE{int to,f,next;
}edge[maxm];inline void build(int a,int b,int w){edge[nedge]=(EDGE){b,w,head[a]};head[a]=nedge++;edge[nedge]=(EDGE){a,0,head[b]};head[b]=nedge++;
}int color[105][105],N,M,S,T,X[4]={0,0,-1,1},Y[4]={1,-1,0,0};bool vis[maxn];
int d[maxn],cur[maxn];bool bfs(){fill(vis,vis+maxn,false);queue<int> q;q.push(S);vis[S]=true;d[S]=0;int u,to;while(!q.empty()){u=q.front();q.pop();for(int k=head[u];k!=-1;k=edge[k].next)if(!vis[to=edge[k].to]&&edge[k].f){d[to]=d[u]+1;vis[to]=true;q.push(to);}}return vis[T];
}int dfs(int u,int minf){if(u==T||!minf) return minf;int flow=0,f,to;if(cur[u]==-2) cur[u]=head[u];for(int& k=cur[u];k!=-1;k=edge[k].next)if(d[to=edge[k].to]==d[u]+1&&(f=dfs(to,min(edge[k].f,minf)))){edge[k].f-=f;edge[k^1].f+=f;flow+=f;minf-=f;if(!minf) break;}return flow;
}int maxflow(){int flow=0;while(bfs()){fill(cur,cur+maxn,-2);flow+=dfs(S,INF);}return flow;
}int main()
{fill(head,head+maxn,-1);N=read();M=read();S=0;T=N*M+1;color[0][0]=1;int x;LL tot=0;for(int i=1;i<=N;i++)for(int j=1;j<=M;j++){if((i%2&&j%2)||(i%2==0&&j%2==0)) color[i][j]=1;else color[i][j]=0;}for(int i=1;i<=N;i++)for(int j=1;j<=M;j++){x=read();tot+=x;if(color[i][j]) build(M*(i-1)+j,T,x);else{build(S,M*(i-1)+j,x);for(int k=0;k<4;k++){int nx=i+X[k],ny=j+Y[k];if(nx>0&&ny>0&&nx<=N&&ny<=M) build(M*(i-1)+j,M*(nx-1)+ny,INF);}}}cout<<tot-maxflow()<<endl;return 0;
}