#include<bits/stdc++.h>

using namespace std;

#define il inline

#define gc getchar()

#define ri register int

#define rc register char

#define rb register bool

#define t(i) edge[i].to

#define fy(i) edge[i].fy

#define w(i) edge[i].wei

#define rp(i,x,y) for(ri i=x;i<=y;++i)

#define e(i,x) for(ri i=head[x];~i;i=edge[i].nxt)

const int N=+;

const int inf=1e9;

int ed_cnt=-,head[N],dep[N],S,T,cur[N],n,m,mvx[]={,,,-},mvy[]={,-,,};

struct ed{int to,nxt,wei;}edge[N];

il int read()

{

    rc ch=gc;ri x=;rb y=;

    while(ch!='-' && (ch<'' || ch>''))ch=gc;

    if(ch=='-')ch=gc,y=;

    while(''<=ch && ch<='')x=(x<<)+(x<<)+(ch^''),ch=gc;

    return y?x:-x;

}

il void ad(ri x,ri y,ri z)

{edge[++ed_cnt]=(ed){x,head[y],z};head[y]=ed_cnt;edge[++ed_cnt]=(ed){y,head[x],};head[x]=ed_cnt;}

il int nam(ri x,ri y){return (x-)*m+y;}

il bool bfs()

{

    queue<int>Q;Q.push(S);memset(dep,,sizeof(dep));dep[S]=;

    while(!Q.empty())

    {ri nw=Q.front();Q.pop();e(i,nw)if(w(i) && !dep[t(i)]){dep[t(i)]=dep[nw]+,Q.push(t(i));if(t(i)==T)return ;}}

    return dep[T];

}

il int dfs(ri nw,ri flow)

{

    if(nw==T || !flow)return flow;ri ret=;

    for(ri &i=cur[nw];~i;i=edge[i].nxt)if(w(i) && dep[t(i)]==dep[nw]+){ri tmp=dfs(t(i),min(flow,w(i)));flow-=tmp,w(i)-=tmp,ret+=tmp,w(i^)+=tmp;}

    if(!ret)dep[nw]=;

    return ret;

}

il int dinic(){ri ret=;while(bfs()){rp(i,S,T)cur[i]=head[i];while(int d=dfs(S,inf))ret+=d;}return ret;}

int main()

{

    memset(head,-,sizeof(head));n=read();m=read();S=;T=n*m+;

    rp(i,,n)rp(j,,m){ri tmp=read();if(tmp==)ad(nam(i,j),S,inf);if(tmp==)ad(T,nam(i,j),inf);}

    rp(i,,n)

        rp(j,,m)rp(k,,){ri tx=i+mvx[k],ty=j+mvy[k];if(tx && ty && tx<=n && ty<=m)ad(nam(i,j),nam(tx,ty),);}

    printf("%d\n",dinic());

    return ;

}