#include<bits/stdc++.h>
using namespace std;

using u64 = unsigned long long;
using u32 = unsigned int;
using i64 = long long;

mt19937_64 rnd(random_device{}());

const int mod = 998244353;
const int N = 3e5 + 5;
const int M = 2e6 + 5;

int n, m, s, t;

template<typename T>
struct Dinic {
	int n;
	vector<int> h, dep, cur;
	int edgeNum = 1;
	struct Edge {
		int to, nxt;
		T rest;
	};
	vector<Edge> adj;
	Dinic(int PointNum) : n(PointNum), h(n + 1), dep(n + 1), cur(n + 1), adj(M) {}
	void add(int u, int v, int w) {
		edgeNum += 1;
		adj[edgeNum] = {v, h[u], w};
		h[u] = edgeNum;
		edgeNum += 1;
		adj[edgeNum] = {u, h[v], 0};
		h[v] = edgeNum;
	}
	bool bfs() {
		for(int i = 1; i <= n; i++) dep[i] = 0;
		queue<int> q;
		q.push(s);
		dep[s] = 1;
		while(q.size()) {
			int u = q.front();
			q.pop();
			for(int i = h[u]; i; i = adj[i].nxt) {
				if(!dep[adj[i].to] && adj[i].rest > 0) {
					dep[adj[i].to] = dep[u] + 1;
					q.push(adj[i].to);
					if(adj[i].to == t) return 1;
				}
			}
		}
		return 0;
	}
	T augment(int u, T limit) {
		if(u == t) return limit;
		T sum = 0;
		for(int i = cur[u]; i; i = adj[i].nxt) {
			cur[u] = i;
			if(dep[adj[i].to] == dep[u] + 1 && adj[i].rest > 0) {
				int flow = augment(adj[i].to, min(limit, adj[i].rest));
				adj[i].rest -= flow;
				adj[i ^ 1].rest += flow;
				sum += flow;
				limit -= flow;
				if(!limit) break;
			}
		}
		if(!sum) dep[u] = 0;
		return sum;
	}
	T dinic() {
		T maxFlow = 0;
		while(bfs()) {
			for(int i = 1; i <= n; i++) cur[i] = h[i];
			maxFlow += augment(s, numeric_limits<T>::max());
		}
		return maxFlow;
	}
};

void RuinGuard(int tc)
{
	cin >> n >> m;
	
	vector idx(n + 1, vector<array<int, 2>>(m + 1));
	
	int nodeNum = 0;
	
	vector mp(n + 1, vector<int>(m + 1));
	for(int i = 1; i <= n; i++) {
		for(int j = 1; j <= m; j++) {
			char c;
			cin >> c;
			if(c == '#') {
				mp[i][j] = 1;
				idx[i][j][0] = ++nodeNum;
				idx[i][j][1] = ++nodeNum;
			}
		}
	}
	
	//cerr << "@" << '\n';
	
	s = nodeNum + 1, t = nodeNum + 2;
	
	Dinic<int> G(nodeNum + 5);
	
	for(int i = 1; i <= m; i++) if(mp[1][i]) G.add(idx[1][i][1], t, 1e9);
	for(int i = 1; i <= n; i++) if(mp[i][m]) G.add(idx[i][m][1], t, 1e9);
	for(int i = 1; i <= m; i++) if(mp[n][i]) G.add(s, idx[n][i][0], 1e9);
	for(int i = 1; i <= n; i++) if(mp[i][1]) G.add(s, idx[i][1][0], 1e9);
	//cerr << '@' << '\n';
	for(int i = 1; i <= n; i++) {
		for(int j = 1; j <= m; j++) {
			if(!mp[i][j]) continue;
			G.add(idx[i][j][0], idx[i][j][1], 1);
			for(int u = max(1, i - 2); u <= min(n, i + 2); u++) {
				for(int v = max(1, j - 2); v <= min(m, j + 2); v++) {
					if(u == i && v == j || !mp[i][j]) continue;
					G.add(idx[i][j][1], idx[u][v][0], 1e9);
				}
			}
		}
	}
	
	cout << G.dinic() << '\n';
}

signed main()
{ 
    ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
    
    int testcase = 1;
	//cin >> testcase;
	
    for(int tc = 1; tc <= testcase; tc++) {
    	RuinGuard(tc);
	}

    return 0;
}