1 #include<cstdio>
  2 #include<cstdlib>
  3 #include<cstring>
  4 #include<iostream>
  5 #include<algorithm>
  6 #include<queue>
  7 #include<cmath>
  8 using namespace std;
  9 #define Maxn 1010
 10 #define INF 0xfffffff
 11 
 12 struct node
 13 {
 14     int x,y,f,o,next;
 15 }t[Maxn*1010];int len;
 16 int first[Maxn];
 17 
 18 int mymin(int x,int y) {return x<y?x:y;}
 19 int mymax(int x,int y) {return x>y?x:y;}
 20 
 21 void ins(int x,int y,int f)
 22 {
 23     t[++len].x=x;t[len].y=y;t[len].f=f;
 24     t[len].next=first[x];first[x]=len;t[len].o=len+1;
 25     t[++len].x=y;t[len].y=x;t[len].f=0;
 26     t[len].next=first[y];first[y]=len;t[len].o=len-1;
 27 }
 28 
 29 int st,ed;
 30 queue<int > q;
 31 int dis[Maxn];
 32 bool bfs()
 33 {
 34     while(!q.empty()) q.pop();
 35     memset(dis,-1,sizeof(dis));
 36     q.push(st);dis[st]=0;
 37     while(!q.empty())
 38     {
 39         int x=q.front();
 40         for(int i=first[x];i;i=t[i].next) if(t[i].f>0)
 41         {
 42             int y=t[i].y;
 43             if(dis[y]==-1)
 44             {
 45                 dis[y]=dis[x]+1;
 46                 q.push(y);
 47             }
 48         }
 49         q.pop();
 50     }
 51     if(dis[ed]==-1) return 0;
 52     return 1;
 53 }
 54 
 55 int ffind(int x,int flow)
 56 {
 57     if(x==ed) return flow;
 58     int now=0;
 59     for(int i=first[x];i;i=t[i].next) if(t[i].f>0)
 60     {
 61         int y=t[i].y;
 62         if(dis[y]==dis[x]+1)
 63         {
 64             int a=ffind(y,mymin(flow-now,t[i].f));
 65             t[i].f-=a;
 66             t[t[i].o].f+=a;
 67             now+=a;
 68         }
 69         if(now==flow) break;
 70     }
 71     if(now==0) dis[x]=-1;
 72     return now;
 73 }
 74 
 75 void output()
 76 {
 77     for(int i=1;i<=len;i+=2)
 78      printf("%d->%d %d\n",t[i].x,t[i].y,t[i].f);
 79 }
 80 
 81 int max_flow()
 82 {
 83     int ans=0;
 84     while(bfs())
 85     {
 86         ans+=ffind(st,INF);
 87     }
 88     return ans;
 89 }
 90 
 91 int bx[6]={0,0,1,0,-1},
 92     by[6]={0,1,0,-1,0};
 93 
 94 int main()
 95 {
 96     int n,m,sum=0;
 97     scanf("%d%d",&n,&m);
 98     st=n*m+1;ed=st+1;
 99     for(int i=1;i<=n;i++)
100      for(int j=1;j<=m;j++)
101      {
102          int x,now=(i-1)*m+j;
103          scanf("%d",&x);
104          sum+=x;
105          if((i+j)%2==0) ins(st,now,x);
106          else ins(now,ed,x);
107      }
108     for(int i=1;i<=n;i++)
109      for(int j=1;j<=m;j++)
110      {
111          int now=(i-1)*m+j;
112          for(int k=1;k<=4;k++) if(i+bx[k]>=1&&i+bx[k]<=n&&j+by[k]>=1&&j+by[k]<=m)
113          {
114              int nn=(i+bx[k]-1)*m+j+by[k];
115              if((i+j)%2==0) ins(now,nn,INF);
116              else ins(nn,now,INF);
117          }
118      }
119     int x=max_flow();
120     printf("%d\n",sum-x);
121     return 0;
122 }