#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 = 3e3 + 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;
}