#include<bits/stdc++.h>
using namespace std;
const int N = 1e4,M = 1e5;
struct Dinic
{
	int s,t,w,ans,dep[N + 5],head[N + 5],nhead[N + 5],cnt;
	queue <int> q;
	struct edge
	{
		int u,v,nxt,w;
	}e[2 * M + 5];
	void adde(int u,int v,int w)
	{
		e[++cnt] = (edge){u,v,head[u],w};
		head[u] = cnt;
	}
	void Adde(int u,int v,int w)
	{
		adde(u,v,w);adde(v,u,0);
	}
	bool bfs()
	{
		while(!q.empty())q.pop();
		q.push(s);
		memset(dep,-1,sizeof(dep));
		dep[s] = 0;
		while(!q.empty())
		{
			int u = q.front();
			q.pop();
			if(u == t)return 1;
			for(int i = head[u];i;i = e[i].nxt)
				if(e[i].w&&dep[e[i].v] == -1)
					dep[e[i].v] = dep[u] + 1,
					q.push(e[i].v);
		}
		return 0;
	}
	int dinic(int u,int s)
	{
		if(u == t)return ans += s,s;
		int tot = 0;
		for(int i = nhead[u];i;i = e[i].nxt)
		{
			nhead[u] = i;
			if(e[i].w&&dep[e[i].v] == dep[u] + 1)
			{
				int now = dinic(e[i].v,min(s - tot,e[i].w));
				e[i].w -= now;e[i ^ 1].w += now;tot += now;
			}
			if(s == tot)return tot;
		}
		return tot;
	}
	void init(int S,int T)
	{
		memset(head,0,sizeof(head));
		ans = 0;cnt = 1;s = S,t = T;
	}
	void main()
	{
		while(bfs())
			memcpy(nhead,head,sizeof(head)),dinic(s,1e9);
	}
}dinic;
int n,m;
char c[N + 5]; 
int id(int x,int y,int k)
{
	return k * n * m + x * m + y - m;
}
int main()
{
	scanf("%d %d",&n,&m);
	int s = id(n,m,1) + 1,t = s + 1;
	dinic.init(s,t);
	for(int i = 1;i <= n;i++)
	{
		scanf("%s",c + 1);
		for(int j = 1;j <= m;j++)
		{
			if(i == 1||j == m)dinic.Adde(s,id(i,j,0),1e6);
			if(i == n||j == 1)dinic.Adde(id(i,j,1),t,1e6);
			if(c[j] == '#')
			{
				dinic.Adde(id(i,j,0),id(i,j,1),1);
				for(int di = -2;di <= 2;di++)
					for(int dj = -2;dj <= 2;dj++)
					{
						int ni = i + di,nj = j + dj;
						if(ni > 0&&ni <= n&&nj > 0&&nj <= m)
							dinic.Adde(id(i,j,1),id(ni,nj,0),1e6);
					}
			}
		}
	}
	dinic.main();
	cout<<dinic.ans<<"\n";
}