#include <bits/stdc++.h>
#define ll long long
#define ID(i,j) (((i)-1)*m+(j))
using namespace std;
int n,m,s,t;
struct edge{int v,next;ll w;edge(){}edge(int _v,ll _w,int _next){v=_v;w=_w;next=_next;}}e[2000011];int head[1000011],sz;
void init(){memset(head,-1,sizeof(head));sz=-1;}void insert(int u,int v,ll w,ll w2=0){e[++sz]=edge(v,w,head[u]);head[u]=sz;e[++sz]=edge(u,w2,head[v]);head[v]=sz;}
int dis[1000011],cur[1000011];bool vis[1000011];
bool bfs()
{
	for(int i=s;i<=t;++i)dis[i]=1e9,vis[i]=0;
	queue<int> q;q.push(s);vis[s]=1;dis[s]=0;//printf("intimb\n");
	while(!q.empty())
	{
		int p=q.front();q.pop();//printf("p:(%d,%d)\n",(p-1)/m+1,(p-1)%m+1);
		for(int i=head[p];~i;i=e[i].next)if(e[i].w&&!vis[e[i].v])
		{
			dis[e[i].v]=dis[p]+1;
			vis[e[i].v]=1;q.push(e[i].v);
		}
	}
	return vis[t];
}
ll dfs(int u,ll fl)
{
	if(u==t||!fl)return fl;ll ans=0;
	for(int &i=cur[u];~i;i=e[i].next)if(e[i].w&&dis[e[i].v]==dis[u]+1)
	{
		ll res=dfs(e[i].v,min(fl,e[i].w));
		ans+=res;e[i].w-=res;e[i^1].w+=res;fl-=res;
		if(!fl)break;
	}
	return ans;
}
ll dinic(){ll ans=0;while(bfs()){for(int i=s;i<=t;++i)cur[i]=head[i];ans+=dfs(s,1e18);}return ans;}
ll C;
char a[111][111];
int dxy[12][2]={{-1,1},{0,1},{0,2},{1,0},{1,1},{2,0},{1,2},{2,1},{2,2},{-1,2},{-2,1},{-2,2}};
int main()
{
	scanf("%d%d",&n,&m);init();
	s=1;t=2*n*m+2;
	for(int i=1;i<=n;++i)scanf("%s",a[i]+1);
	for(int i=1;i<=n;++i)
	{
		for(int j=1;j<=m;++j)
		{
			for(int _=0;_<12;++_)
			{
				int ni=i+dxy[_][0],nj=j+dxy[_][1];
				if(ni<=0||nj<=0||ni>n||nj>m)continue;
				insert(ID(i,j)*2+1,ID(ni,nj)*2,1e9);
				insert(ID(ni,nj)*2+1,ID(i,j)*2,1e9);
			}
		}
	}
	for(int i=1;i<=m;++i)insert(s,2*ID(1,i),1e9),insert(2*ID(n,i)+1,t,1e9);
	for(int i=1;i<=n;++i)insert(s,2*ID(i,m),1e9),insert(2*ID(i,1)+1,t,1e9);
	for(int i=1;i<=n;++i)
	{
		for(int j=1;j<=m;++j)if(a[i][j]=='#')
		{
			insert(2*ID(i,j),2*ID(i,j)+1,1);
		}
	}
	printf("%lld\n",dinic());
}