#include <bits/stdc++.h>
using namespace std;
#define V vector
#define all0(x) (x).begin(),(x).end()
#define all1(x) (x).begin()+1,(x).end()
#define pb push_back
#define fi first
#define se second
#define lb lower_bound
#define ub upper_bound
#define cin std::cin
#define cout std::cout
typedef long long LL;
typedef pair<int, int> pi;
typedef pair<LL, LL> pl;

//const int MN = 2e5 + 20;
const int INF = 2e9 + 1000;//INF
const LL INFLL = 8e18 + 1000;//INF long long 
mt19937 mrand(chrono::steady_clock().now().time_since_epoch().count());
//模板区域~~~~~~~
template<class T> //流的类型
struct flow{
    static const int N = 2e5 + 1000;
    static const int E = 2e5 + 1000;
    int s, t, vtot;
    int h[N], etot;
    int dis[N], cur[N];
    struct edge{
        int v,nxt;
        T f;
    }e[E * 2];
    void add(int u, int v, T f){
        e[etot] = {v, h[u], f};
        h[u] = etot++;
        e[etot] = {u, h[v], 0};
        h[v] = etot++;
    }

    bool bfs(){
        for(int i = 1; i <= vtot; i++){
            dis[i] = 0;
            cur[i] = h[i];
        }
        queue<int> que;
        que.push(s);
        dis[s] = 1;
        while(que.size()){
            int u = que.front();
            que.pop();
            for(int i = h[u]; ~i; i = e[i].nxt){
                if(e[i].f && !dis[e[i].v]){
                    int v = e[i].v;
                    dis[v] = dis[u] + 1;
                    if(v == t) return 1;
                    que.push(v);
                }
            }
        }
        return 0;
    }

    T dfs(int u, T m){
        if(u == t) return m;
        LL flow = 0;
        for(int i = cur[u]; ~i; cur[u] = i = e[i].nxt)
            if(e[i].f && dis[e[i].v] == dis[u] + 1){
                T f = dfs(e[i].v, min(m,e[i].f));
                e[i].f -= f;
                e[i ^ 1].f += f;
                m -= f;
                flow += f;
                if(!m) break;
            }
        if(!flow) dis[u] = -1;
        return flow;
    }
    T dinic(){
        T flow = 0;
        while(bfs()) flow += dfs(s,numeric_limits<T>::max());
        return flow;
    }
    void ini(int ss, int tt, int vt){
        s = ss;
        t = tt;
        vtot = vt;
        etot = 0;
        for(int i = 1; i <= vtot; i++) h[i] = -1;
    }
};
flow<int> f;
//模板结束~~~~~~~

void solve() {
    int n; cin >> n;
    int m; cin >> m;
    V<string> vs(n + 1);
    for(int i =1 ; i <= n; i++) cin >> vs[i], vs[i] = " " + vs[i];

    int s = 3 * (n * m) + 1, t = s + 1;
    f.ini(s, t, t);

    auto id = [&](int x, int y, int type) -> int {
        if(y <= 0 || x >= n + 1) return s;
        if(y >= m + 1 || x <= 0) return t;
        return x + (y - 1) * n + type * n * m;
    };

    for(int i = 1; i <= n; i++) {
        for(int j = 1; j <= m; j++) {
            if(vs[i][j] == '#') {
                for(int dx = -1; dx <= 1; dx++) {
                    for(int dy = -1; dy <= 1; dy++) {
                        if(dx == 0 && dy == 0) continue;
                        f.add(id(i, j, 1), id(i + dx, j + dy, 0), INF);
                        f.add(id(i + dx, j + dy, 0), id(i, j, 2), INF);
                    }
                }
                f.add(id(i, j, 0), id(i, j, 1), 1);
                f.add(id(i, j, 2), id(i, j, 0), 1);
            }
        }
    }

    cout << f.dinic() << endl;
}

int32_t main() {
    ios::sync_with_stdio(0),cin.tie(0),cout.tie(0);
    int t=1;
    //cin >> t;
    while (t--) 
    solve();
}