1 //minamoto
 2 #include<iostream>
 3 #include<cstdio>
 4 #include<cstring>
 5 #include<queue>
 6 #define inf 0x3f3f3f3f
 7 using namespace std;
 8 #define getc() (p1==p2&&(p2=(p1=buf)+fread(buf,1,1<<21,stdin),p1==p2)?EOF:*p1++)
 9 char buf[1<<21],*p1=buf,*p2=buf;
10 inline int read(){
11     #define num ch-'0'
12     char ch;bool flag=0;int res;
13     while(!isdigit(ch=getc()))
14     (ch=='-')&&(flag=true);
15     for(res=num;isdigit(ch=getc());res=res*10+num);
16     (flag)&&(res=-res);
17     #undef num
18     return res;
19 }
20 const int N=10005,M=1000005;
21 int head[N],Next[M],ver[M],edge[M],tot=1;
22 int cur[N],dep[N],id[105][105],mp[105][105];
23 int n,m,S,T;
24 queue<int> q;
25 int dx[]={1,-1,0,0},dy[]={0,0,1,-1};
26 inline void add(int u,int v,int e){
27     ver[++tot]=v,Next[tot]=head[u],head[u]=tot,edge[tot]=e;
28     ver[++tot]=u,Next[tot]=head[v],head[v]=tot,edge[tot]=0;
29 }
30 bool bfs(){
31     memset(dep,-1,sizeof(dep));
32     for(int i=S;i<=T;++i) cur[i]=head[i];
33     while(!q.empty()) q.pop();
34     q.push(S),dep[S]=0;
35     while(!q.empty()){
36         int u=q.front();q.pop();
37         for(int i=head[u];i;i=Next[i]){
38             int v=ver[i];
39             if(edge[i]&&dep[v]<0){
40                 dep[v]=dep[u]+1,q.push(v);
41                 if(v==T) return true;
42             }
43         }
44     }
45     return false;
46 }
47 int dfs(int u,int limit){
48     if(u==T||!limit) return limit;
49     int flow=0,f;
50     for(int &i=cur[u];i;i=Next[i]){
51         int v=ver[i];
52         if(dep[v]==dep[u]+1&&(f=dfs(v,min(limit,edge[i])))){
53             flow+=f,limit-=f;
54             edge[i]-=f,edge[i^1]+=1;
55             if(!limit) break;
56         }
57     }
58     return flow;
59 }
60 int dinic(){
61     int flow=0;
62     while(bfs()) flow+=dfs(S,inf);
63     return flow;
64 }
65 void build(){
66     for(int i=1;i<=n;++i)
67     for(int j=1;j<=m;++j){
68         if(!mp[i][j]) continue;
69         (mp[i][j]&1)?add(id[i][j],T,inf):add(S,id[i][j],inf);
70     }
71     for(int i=1;i<=n;++i)
72     for(int j=1;j<=m;++j){
73         if(mp[i][j]&1) continue;
74         for(int k=0;k<4;++k){
75             int xx=i+dx[k],yy=j+dy[k];
76             if(xx<1||xx>n||yy<1||yy>m||(mp[xx][yy]&2)) continue;
77             add(id[i][j],id[xx][yy],1);
78         }
79     }
80 }
81 int main(){
82 //    freopen("testdata.in","r",stdin);
83     n=read(),m=read();
84     for(int i=1;i<=n;++i)
85     for(int j=1;j<=m;++j)
86     mp[i][j]=read(),id[i][j]=(i-1)*m+j;
87     S=0,T=n*m+1;
88     build();
89     printf("%d\n",dinic());
90     return 0;
91 }