#include<bits/stdc++.h>
#define rep(i, n) for(int i = 0; i < (n); ++i)
using namespace std;
typedef long long ll;
typedef vector<int> vi;
typedef pair<int, int> pii;
const int Mod = 998244353;
inline void uadd(int &a, const int &b){ a += b - Mod; a += (a>>31) & Mod; }
inline int add(int a, const int &b){ a += b - Mod; a += (a>>31) & Mod; return a; }
inline void usub(int &a, const int &b){ a -= b; a += (a>>31) & Mod; }
inline int sub(int a, const int &b){ a -= b, a += (a>>31) & Mod; return a; }
inline void umul(int &a, const int &b){ a = (int)(1ll * a * b % Mod); }
inline int mul(const int &a, const int &b){ return (int)(1ll * a * b % Mod); }
int qpow(int b, ll p){ int ret = 1; while(p){ if(p & 1) umul(ret, b); umul(b, b), p >>= 1; } return ret; }
const int fN = 10010;
int fact[fN], invfact[fN], inv[fN];
void initfact(int n){
	fact[0] = 1; for(int i = 1; i <= n; ++i) fact[i] = mul(fact[i - 1], i);
	invfact[n] = qpow(fact[n], Mod - 2); for(int i = n; i > 0; --i) invfact[i - 1] = mul(invfact[i], i);
	for(int i = 1; i <= n; ++i) inv[i] = mul(invfact[i], fact[i - 1]);
}
inline int binom(int n, int m){ return mul(fact[n], mul(invfact[m], invfact[n - m])); }

const int inf = 0x3f3f3f3f;
const ll INF = 0x3f3f3f3f3f3f3f3fll;
template<typename T> inline void chmax(T &_a, const T &_b){ (_b>_a) ? (_a=_b) : _a; }
template<typename T> inline void chmin(T &_a, const T &_b){ (_b<_a) ? (_a=_b) : _a; }

namespace mf{
	int cn, cur[1000100], hd[1000100]; ll dis[1000100];
	int ce, to[1000100], nxt[1000100]; ll cap[1000100];
	void clr(int n){
		//cout << "------clr-------" << endl;
		cn = n, ce = 0;
		fill(hd, hd+cn, -1);
	}
	void ae(int f, int t, ll c){
		//cout << "ae " << f << " " << t << " " << c << " " << inf-c << endl;
		nxt[ce] = hd[f], cap[ce] = c, to[ce] = t, hd[f] = ce++;
		nxt[ce] = hd[t], cap[ce] = 0, to[ce] = f, hd[t] = ce++;
	}
	bool bfs(int S, int T){
		fill(dis, dis+cn, inf);
		dis[S] = 0;
		queue<int> q;
		q.emplace(S);
		while(!q.empty()){
			int u = q.front(); q.pop();
			//cout << "bfs " << u << endl;
			for(int eid = hd[u]; eid >= 0; eid = nxt[eid]){
				int t = to[eid];
				if(dis[t] > dis[u] + 1 && cap[eid]){
					dis[t] = dis[u] + 1;
					q.emplace(t);
				}
			}
		}
		//cout << cn << " " << S << " " << T << ": " << dis[T] << endl;
		return dis[T] < inf;
	}
	ll dfs(int u, int dest, ll flow){
		//cout << "dfs " << u << endl;
		if(u == dest) return flow;
		ll nf = flow;
		for(int &eid = cur[u]; eid >= 0; eid = nxt[eid]){
			int t = to[eid];
			if(cap[eid] && dis[t] == dis[u] + 1){
				ll ret = dfs(t, dest, min(nf, cap[eid]));
				nf -= ret, cap[eid] -= ret, cap[eid^1] += ret;
				if(!nf) break;
			}
		}
		return flow - nf;
	}
	ll mf(int S, int T){
		ll ans = 0;
		while(bfs(S, T)){
			rep(i, cn) cur[i] = hd[i];
			ans += dfs(S, T, inf);
			//cout << ans << endl;
		}
		return ans;
	}
}

int n, m;
string s[55];
vector<pii> o;

int main(){
	ios::sync_with_stdio(false);
	cin.tie(0);

	cin >> n >> m;
	rep(i, n) cin >> s[i];
	rep(i, n) rep(j, m) if(s[i][j] == '#') o.push_back(make_pair(i, j));
	int k = (int)o.size();
	mf::clr(2 + 2 * k);
	rep(i, k){
		int x = o[i].first, y = o[i].second;
		mf::ae(2 + i, 2 + k + i, 1);
		if(x == 0 || y == m - 1) mf::ae(0, 2 + i, 1);
		if(x == n - 1 || y == 0) mf::ae(2 + k + i, 1, 1);
		rep(j, k) if(j != i){
			int tx = o[j].first, ty = o[j].second;
			if(tx >= x - 2 && tx <= x + 2 && ty >= y - 2 && ty <= y + 2)
				mf::ae(2 + k + i, 2 + j, 1);
		}
	}
	cout << mf::mf(0, 1) << "\n";

	return 0;
}