//Lib
#include<cstdio>
#include<cstring>
#include<cstdlib>
#include<cmath>
#include<ctime>
 
#include<iostream>
#include<algorithm>
#include<vector>
#include<string>
#include<queue>
#include<set>
#include<map>
using namespace std;
//Macro
#define rep(i,a,b)  for(int i=a,tt=b;i<=tt;++i)
#define drep(i,a,b) for(int i=a,tt=b;i>=tt;--i)
#define erep(i,e,x) for(int i=x;i;i=e[i].next)
#define irep(i,x)   for(__typeof(x.begin()) i=x.begin();i!=x.end();i++)
#define read()  (strtol(ipos,&ipos,10))
#define sqr(x)  ((x)*(x))
#define pb  push_back
#define PS  system("pause");
typedef long long   ll;
typedef pair<int,int> pii;
const int oo=~0U>>1;
const double inf=1e100;
const double eps=1e-6;
string name="ws", in=".in", out=".out";
//Var
queue<int> q;
struct E
{
    int next,node,cap;  
}e[100008];
int h[100008],node[108][108],dis[10008];
int n,m,cnt,ans,st,ed,tot=1;
void add(int a,int b,int c)
{
    e[++tot].next=h[a];e[tot].node=b;e[tot].cap=c;h[a]=tot;
    e[++tot].next=h[b];e[tot].node=a;e[tot].cap=0;h[b]=tot;
}
void Init()
{
    scanf("%d%d",&n,&m);
    rep(i,1,n)rep(j,1,m)node[i][j]=++cnt;
    st=++cnt;ed=++cnt;int a;
    rep(i,1,n)rep(j,1,m)
    {
        if(i!=n)add(node[i][j],node[i+1][j],1);
        if(j!=m)add(node[i][j],node[i][j+1],1);
        if(i!=1)add(node[i][j],node[i-1][j],1);
        if(j!=1)add(node[i][j],node[i][j-1],1);
    }
    rep(i,1,n)rep(j,1,m)
    {
        scanf("%d",&a);
        if(a==1)add(st,node[i][j],oo);
        else if(a==2) add(node[i][j],ed,oo);
    }
}
bool BFS()
{
    memset(dis,-1,sizeof dis);
    dis[ed]=0;q.push(ed);
    int u,v;bool flag=false;
    while(!q.empty())
    {
        u=q.front();q.pop();
        erep(i,e,h[u])
        {
            if(dis[v=e[i].node]!=-1||!e[i^1].cap)continue;
            dis[v]=dis[u]+1;
            if(v==st)flag=true;
            q.push(v);
        }
    }
    return flag;
}
int DFS(int u,int low)
{
    if(u==ed)return low;
    int v,tmp,ret=low;
    erep(i,e,h[u])
    {
        if(dis[v=e[i].node]!=dis[u]-1||!e[i].cap)continue;
        tmp=DFS(v,min(e[i].cap,low));
        e[i].cap-=tmp;
        e[i^1].cap+=tmp;
        low-=tmp;
        if(low==0)break;
    }
    if(ret==low)dis[u]=-1;
    return ret-low;
}
void Work()
{
    int flow;
    while(BFS())
        while(flow=DFS(st,oo))
            ans+=flow;  
    cout<<ans<<endl;
}
int main()
{
//  freopen((name+in).c_str(),"r",stdin);
//  freopen((name+out).c_str(),"w",stdout);
    Init();
    Work();
    return 0;
}