#include <bits/stdc++.h>
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/hash_policy.hpp>
#define sz(vec) ((ll)vec.size())
#define all(vec) vec.begin(),vec.end()
#define umap __gnu_pbds::gp_hash_table
using ll = long long;
using i128 = __int128;
using db = double;
#define Emu Smile
using namespace std;

void chmax(auto &a, auto b) { if (a < b) a = b; }
void chmin(auto &a, auto b) { if (a > b) a = b; }
inline int lbt(int x) { return x & (-x); }

const int P = 1e9+7, B = 1000;
const ll inf = 1e4;

struct Flow {
	static const ll inf = 1e18;
	int n; vector<int> cur,dep;
	struct Edge {
		int v; ll c;
		Edge(int v,ll c):v(v),c(c) {}
	};
	vector<Edge> e; vector<vector<int>> g;
	Flow(int n):n(n),g(n){}
	void add(int u,int v,ll c) {
		g[u].emplace_back(sz(e)); e.emplace_back(v,c);
		g[v].emplace_back(sz(e)); e.emplace_back(u,0);
	}
	// 先跑个层次图
	bool bfs(int s,int t) {
		cur.assign(n,0); dep.assign(n,-1);
		queue<int> q;
		dep[s] = 0; q.emplace(s);
		while (!q.empty()) {
			int u = q.front(); q.pop();
			for (auto i:g[u]) {
				auto [v,c] = e[i];
				if (dep[v] == -1 && c > 0) {
					dep[v] = dep[u] + 1;
					q.emplace(v);
				}
			}
		}
		// 如果不存在到达t的路径，则增广结束
		return dep[t] != -1;
	}
	ll dfs(int u,int t,ll f) {
		if (!f || u == t) return f;
		ll res = 0;
		for (int &i = cur[u]; i < sz(g[u]); ++i) {
			int j = g[u][i]; ll k;
			auto [v,c] = e[j];
			if (dep[v] == dep[u]+1 && (k = dfs(v,t,std::min<ll>(f,c))) > 0) {
				f -= k; res += k;
				e[j].c -= k; e[j^1].c += k;
				if (!f) break;
			}
		}
		return res;
	}
	ll dinic(int s,int t) {
		ll res = 0;
		while (bfs(s,t)) res += dfs(s,t,inf);
		return res;
	}
	vector<pair<int,int>> getcut(int s,int t) {
		std::vector<int> vis(n);
		auto dfs = [&](auto &self,int u) -> void {
			for (auto x : g[u]) {
				if (e[x].c && !vis[e[x].v]) {
					vis[e[x].v] = 1;
					self(self, e[x].v);
				}
			}
		};
		dfs(dfs,s);
		vector<pair<int,int>> ret;
		for (int u = 0; u < n; ++u) {
			if (!vis[u]) continue;
			for (auto x : g[u]) {
				if (x % 2 == 0 && !vis[e[x].v]) {
					ret.emplace_back(u,x);
				}
			}
		}
		return ret;
	}
};

void solve() {
	int n,m; cin >> n >> m;
	vector<string> str(n);
	for (int i = 0; i < n; ++i) {
		cin >> str[i];
	}
	int cnt = n * m * 2, s = cnt++, t = cnt++;
	auto getid = [&](int i,int j,int inout) -> int {
		return (i * m + j) * 2 + inout;
	};
	Flow flow(cnt);
	for (int i = 0; i < n; ++i) {
		flow.add(s, getid(i, m-1, 0), flow.inf);
		flow.add(getid(i, 0, 1), t, flow.inf);
	}
	for (int i = 0; i < m; ++i) {
		flow.add(s, getid(0, i, 0), flow.inf);
		flow.add(getid(n-1, i, 1), t, flow.inf);
	}
	auto islegal = [&](int i,int j) -> bool {
		return i >= 0 && j >= 0 && i < n && j < m;
	};
	for (int i = 0; i < n; ++i) {
		for (int j = 0; j < m; ++j) {
			if (str[i][j] == '#') {
				flow.add(getid(i, j, 0), getid(i, j, 1), 1);
			}
			for (int k = -2; k <= 2; ++k) {
				for (int l = -2; l <= 2; ++l) {
					int ni = i + k, nj = j + l;
					if (!islegal(ni, nj) || (ni == i && nj == j)) continue;
					flow.add(getid(i, j, 1), getid(ni, nj, 0), flow.inf);
				}
			}
		}
	}
	ll ret = flow.dinic(s, t);
	cout << ret << '\n';
}

int main() {

	ios::sync_with_stdio(false);
	cin.tie(nullptr);

//	freopen("test.in","r",stdin);
//	freopen("test.out","w",stdout);

//	init();

	cout << fixed << setprecision(10);

	int OuO = 1;
//	cin >> OuO;
	for (int piastic = 0; piastic < OuO; ++piastic) {
		solve();
	}
	return 0;
}