#include <cstdio>
#include <cstring>
#include <vector>
#include <set>
#include <algorithm>

#define X first
#define Y second
#define PB push_back
#define sz(x) ((int)(x).size())

using namespace std;

typedef long long ll;
typedef pair < int, int > pii;
typedef vector < int > vi;

const int N = 54;
const int M = 1e5 + 500;
const int INF2 = 0x3f3f3f3f;

int A[N][N];

const ll INF = (1LL << 60);

struct Dinic {
	struct Edge {
		int to, rev;
		ll c, oc;
		ll flow() { return max(oc - c, 0LL); }
	};
	vi lvl, ptr, q;
	vector<vector<Edge>> adj;
	Dinic(int n) : lvl(n), ptr(n), q(n), adj(n) {}
	void addEdge(int a, int b, ll c, ll rcap = 0) {
		adj[a].push_back({b, sz(adj[b]), c, c});
		adj[b].push_back({a, sz(adj[a]) - 1, rcap, rcap});
	}
	ll dfs(int v, int t, ll f) {
		if(v == t || !f) return f;
		for(int &i = ptr[v]; i < sz(adj[v]);i++) {
			Edge& e = adj[v][i];
			if (lvl[e.to] == lvl[v] + 1) {
				if(ll p = dfs(e.to, t, min(f, e.c))) {
					e.c -= p, adj[e.to][e.rev].c += p;
					return p;
				}
			}
		}
		return 0;
	}
	
	ll calc(int s, int t) {
		ll flow = 0; q[0] = s;
		for(int L = 0;L < 31;L++) do {
			lvl = ptr = vi(sz(q));
			int qi = 0, qe = lvl[s] = 1;
			while(qi < qe && !lvl[t]) {
				int v = q[qi++];
				for (Edge e : adj[v]) {
					if(!lvl[e.to] && e.c >> (30 - L)) {
						q[qe++] = e.to, lvl[e.to] = lvl[v] + 1;
					}
				}
			}		
			while (ll p = dfs(s, t, INF)) flow += p;
		} while(lvl[t]);
		return flow;
	}
};

int n, m;
char s[N][N];
vector < pii > v;
int dis[M];


int main() {
	scanf("%d%d", &n, &m);
	for(int i = 0;i < n;i++) scanf("%s", s[i]);
	for(int i = 0;i < n;i++) {
		for(int j = 0;j < m;j++) {
			if(s[i][j] == '#') v.PB({i, j});
		}
	}
	Dinic D(2 * (int)v.size() + 2);
	//D.addEdge(0, 1, 0);
	for(int i = 0;i < (int)v.size();i++) {
		D.addEdge(2 * i + 2, 2 * i + 3, 1);
		if(v[i].X == n - 1 || v[i].Y == 0) {
			D.addEdge(0, 2 * i + 2, 1);
		}
		if(v[i].X == 0 || v[i].Y == m - 1) {
			D.addEdge(2 * i + 3, 1, 1);
		}
	}
	for(int i = 0;i < (int)v.size();i++) {
		for(int j = i + 1;j < (int)v.size();j++) {
			int dist = max(abs(v[i].X - v[j].X), abs(v[j].Y - v[i].Y));
			if(dist <= 2) {
				D.addEdge(2 * i + 3, 2 * j + 2, 1);
				D.addEdge(2 * j + 3, 2 * i + 2, 1);
			}
		}
	}
	printf("%lld\n", D.calc(0, 1));
	return 0;
}