#include<bits/stdc++.h>
	using namespace std;
	const long long inf = 1e18;
	const int mininf = 1e9 + 7;
	#define int long long
	#define pb emplace_back
	inline int read(){int x=0,f=1;char ch=getchar();while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}while(ch>='0'&&ch<='9'){x=(x<<1)+(x<<3)+(ch^48);ch=getchar();}return x*f;}
	inline void write(int x){if(x<0){x=~(x-1);putchar('-');}if(x>9)write(x/10);putchar(x%10+'0');}
	#define put() putchar(' ')
	#define endl puts("")
	const int MAX = 6e3 + 10;
	int psz = 2;
	
	struct flow{
		struct node{
			int v, w, cp;
		}; vector <node> g[MAX];
		
		int dis[MAX];
		
		bool bfs(int s, int t){
			for(int i = 1; i <= psz; i++)	dis[i] = mininf;
			dis[s] = 0;
			queue <int> q;
			q.push(s);
			while(!q.empty()){
				int u = q.front();
				q.pop();
				for(auto V : g[u]){
					if(V.w > 0 and dis[V.v] > dis[u] + 1){
						dis[V.v] = dis[u] + 1;
						q.push(V.v);
					}
				}
			}
			if(dis[t] == mininf)	return 0;
			return 1;
		}
		
		int cur[MAX];
		
		int aug(int u, int now, int t){
			if(u == t)	return now;
			int ans = 0;
			for(int &i = cur[u]; i < g[u].size(); i++){
				int v = g[u][i].v, w = g[u][i].w, cp = g[u][i].cp;
				if(dis[v] != dis[u] + 1)	continue;
				int ret = aug(v, min(w, now), t);
				g[u][i].w -= ret, g[v][cp].w += ret;
				now -= ret, ans += ret;
				if(now <= 0)	break;
			}
			return ans;
		}
		
		void add_edge(int u, int v, int w){
			g[u].pb(node{v, w, g[v].size()});
			g[v].pb(node{u, 0, g[u].size() - 1});
		}
	}; flow G;
	      
	int id[55][55][2];
	
	int a[55][55];
	
	
	void solve(){
		int n = read(), m = read();
		int s = 1, t = 2;
		for(int i = 1; i <= n; i++){
			for(int j = 1; j <= m; j++){
				char ch = getchar();
				while(ch != '.' and ch != '#'){
					ch = getchar();
				}
				if(ch == '#'){
					a[i][j] = 1;
					id[i][j][0] = ++psz, id[i][j][1] = ++psz;
				}
			}
		}
		for(int i = 1; i <= m; i++)	if(a[1][i])	G.add_edge(id[1][i][1], t, inf);
		for(int i = 1; i <= n; i++)	if(a[i][1])	G.add_edge(s, id[i][1][0], inf);
		for(int i = 1; i <= m; i++)	if(a[n][i])	G.add_edge(s, id[n][i][0], inf);
		for(int i = 1; i <= n; i++)	if(a[i][m])	G.add_edge(id[i][m][1], t, inf);
		for(int i = 1; i <= n; i++){
			for(int j = 1; j <= m; j++){
				if(!a[i][j])	continue;
				G.add_edge(id[i][j][0], id[i][j][1], 1);
				for(int k = max(1ll, i - 2); k <= min(n, i + 2); k++){
					for(int k2 = max(1ll, j - 2); k2 <= min(m, j + 2); k2++){
						if(k == i and k2 == j)	continue;
						if(a[k][k2]){
							G.add_edge(id[i][j][1], id[k][k2][0], inf);
						}
					}
				}
			}
		}
		int ans = 0;
		while(G.bfs(s, t)){
			for(int i = 1; i <= psz; i++)	G.cur[i] = 0;
			ans += G.aug(s, inf, t);
		}
		write(ans), endl;
	}
	
	signed main(){
		int t = 1;
		while(t--)	solve();
		return 0;
	}