#include <bits/stdc++.h>using namespace std;
const int MAXN=10005,MAXM=40005,INF=1<<27;
namespace Max_Flow
{int head[MAXN],S,T,level[MAXN],iter[MAXN],tot=-1;struct edge{int nxt,to,cap;}e[MAXM<<2];void add_edge(int from,int to,int cap){e[++tot].nxt=head[from];e[tot].to=to;e[tot].cap=cap;head[from]=tot;e[++tot].nxt=head[to];e[tot].to=from;e[tot].cap=0;head[to]=tot;}    bool bfs(){memset(level,-1,sizeof(level));queue<int> q;q.push(S);level[S]=0;while(!q.empty()){int u=q.front();q.pop();for(int i=head[u];i!=-1;i=e[i].nxt)if(e[i].cap && level[e[i].to]==-1)level[e[i].to]=level[u]+1,q.push(e[i].to);}return (level[T]!=-1);}    int dfs(int v,int f){if(v==T) return f;int ret=0;for(int &i=iter[v];i!=-1;i=e[i].nxt){if(level[e[i].to]==level[v]+1 && e[i].cap){int d=dfs(e[i].to,min(f,e[i].cap));e[i].cap-=d;e[i^1].cap+=d;f-=d;ret+=d;if(!f) break;}}return ret;}    int Dinic(){int ret=0;while(bfs()){for(int i=0;i<MAXN;i++) iter[i]=head[i];ret+=dfs(S,INF);}return ret;}
}int dx[]={1,-1,0,0},dy[]={0,0,1,-1};
int n,m,dat[105][105];int main()
{using namespace Max_Flow;S=0;T=10001;memset(head,-1,sizeof(head));scanf("%d%d",&n,&m);for(int i=1;i<=n;i++)for(int j=1;j<=m;j++)scanf("%d",&dat[i][j]);for(int i=1;i<=n;i++)for(int j=1;j<=m;j++){if(dat[i][j]==1) add_edge(S,(i-1)*m+j,INF);if(dat[i][j]==2){add_edge((i-1)*m+j,T,INF);continue;}for(int k=0;k<4;k++){int fx=i+dx[k],fy=j+dy[k];if(fx<1||fx>n||fy<1||fy>m) continue;if(dat[i][j]!=1 || dat[fx][fy]!=1)add_edge((i-1)*m+j,(fx-1)*m+fy,1);}}printf("%d",Dinic());return 0;
}