#include<set>

 #include<cmath>

 #include<queue>

 #include<vector>

 #include<cstdio>

 #include<cstring>

 #include<iostream>

 #include<algorithm>

 #define trav(u,i) for(int i=front[u];i;i=e[i].nxt)

 #define FOR(a,b,c) for(int a=(b);a<=(c);a++)

 using namespace std;

 typedef long long ll;

 const int N = 2e2+;

 const int inf = 1e9;

 ll read() {

     char c=getchar();

     ll f=,x=;

     while(!isdigit(c)) {

         if(c=='-') f=-; c=getchar();

     }

     while(isdigit(c))

         x=x*+c-'',c=getchar();

     return x*f;

 }

 struct Edge {

     int u,v,cap,flow;

 };

 struct Dinic {

     int n,m,s,t;

     int d[N],cur[N],vis[N];

     vector<int> g[N];

     vector<Edge> es;

     queue<int> q;

     void init(int n) {

         this->n=n;

         es.clear();

         FOR(i,,n) g[i].clear();

     }

     void AddEdge(int u,int v,int w) {

         es.push_back((Edge){u,v,w,});

         es.push_back((Edge){v,u,,});

         m=es.size();

         g[u].push_back(m-);

         g[v].push_back(m-);

     }

     int bfs() {

         memset(vis,,sizeof(vis));

         q.push(s); d[s]=; vis[s]=;

         while(!q.empty()) {

             int u=q.front(); q.pop();

             FOR(i,,(int)g[u].size()-) {

                 Edge& e=es[g[u][i]];

                 int v=e.v;

                 if(!vis[v]&&e.cap>e.flow) {

                     vis[v]=;

                     d[v]=d[u]+;

                     q.push(v);

                 }

             }

         }

         return vis[t];

     }

     int dfs(int u,int a) {

         if(u==t||!a) return a;

         int flow=,f;

         for(int& i=cur[u];i<g[u].size();i++) {

             Edge& e=es[g[u][i]];

             int v=e.v;

             if(d[v]==d[u]+&&(f=dfs(v,min(a,e.cap-e.flow)))>) {

                 e.flow+=f;

                 es[g[u][i]^].flow-=f;

                 flow+=f; a-=f;

                 if(!a) break;

             }

         }

         return flow;

     }

     int MaxFlow(int s,int t) {

         this->s=s,this->t=t;

         int flow=;

         while(bfs()) {

             memset(cur,,sizeof(cur));

             flow+=dfs(s,inf);

         }

         return flow;

     }

 } dc;

 int n,m,sum,a[N][N],id[N][N];

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

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

 int main()

 {

     n=read(),m=read();

     FOR(i,,n) FOR(j,,m)

         a[i][j]=read(),sum+=a[i][j],id[i][j]=(i-)*m+j;

     dc.init(n*m+);

     int S=,T=n*m+;

     FOR(i,,n) FOR(j,,m)

         if((i+j)&) {

             dc.AddEdge(S,id[i][j],a[i][j]);

             FOR(k,,) {

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

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

                 dc.AddEdge(id[i][j],id[x][y],inf);

             }

         } else dc.AddEdge(id[i][j],T,a[i][j]);

     printf("%d\n",sum-dc.MaxFlow(S,T));

     return ;

 }