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

#define ll long long
#define elif else if
#define vi vector<int>
#define vll vector<ll>
#define vvi vector<vi>
#define pii pair<int,int>


#define repname(a, b, c, d, e, ...) e
#define rep(...)                    repname(__VA_ARGS__, rep3, rep2, rep1, rep0)(__VA_ARGS__)
#define rep0(x)                     for (int rep_counter = 0; rep_counter < (x); ++rep_counter)
#define rep1(i, x)                  for (int i = 0; i < (x); ++i)
#define rep2(i, l, r)               for (int i = (l); i < (r); ++i)
#define rep3(i, l, r, c)            for (int i = (l); i < (r); i += (c))





struct ScalarInput {
    template<class T>
    operator T(){
        T ret;
        cin >> ret;
        return ret;
    }
};
struct VectorInput {
    size_t n;
    VectorInput(size_t n): n(n) {}
    template<class T>
    operator vector<T>(){
        vector<T> ret(n);
        for(T &x : ret) cin >> x;
        return ret;
    }
};
ScalarInput input(){ return ScalarInput(); }
VectorInput input(size_t n){ return VectorInput(n); }

template<typename T>
void print(vector<T> a){
  for(int i=0;i<a.size();i++){
    cout<<a[i]<<" \n"[i+1==a.size()];
  }
}

template<class T>
void print(T x){
    cout << x << '\n';
}
 
template <class Head, class... Tail>
void print(Head&& head, Tail&&... tail){
  cout << head << ' ';
  print(forward<Tail>(tail)...);
}


#include <algorithm>
#include <cassert>
#include <limits>
#include <queue>
#include <vector>


#include <vector>

namespace atcoder {

namespace internal {

template <class T> struct simple_queue {
    std::vector<T> payload;
    int pos = 0;
    void reserve(int n) { payload.reserve(n); }
    int size() const { return int(payload.size()) - pos; }
    bool empty() const { return pos == int(payload.size()); }
    void push(const T& t) { payload.push_back(t); }
    T& front() { return payload[pos]; }
    void clear() {
        payload.clear();
        pos = 0;
    }
    void pop() { pos++; }
};

}  // namespace internal

}  // namespace atcoder


namespace atcoder {

template <class Cap> struct mf_graph {
  public:
    mf_graph() : _n(0) {}
    explicit mf_graph(int n) : _n(n), g(n) {}

    int add_edge(int from, int to, Cap cap) {
        assert(0 <= from && from < _n);
        assert(0 <= to && to < _n);
        assert(0 <= cap);
        int m = int(pos.size());
        pos.push_back({from, int(g[from].size())});
        int from_id = int(g[from].size());
        int to_id = int(g[to].size());
        if (from == to) to_id++;
        g[from].push_back(_edge{to, to_id, cap});
        g[to].push_back(_edge{from, from_id, 0});
        return m;
    }

    struct edge {
        int from, to;
        Cap cap, flow;
    };

    edge get_edge(int i) {
        int m = int(pos.size());
        assert(0 <= i && i < m);
        auto _e = g[pos[i].first][pos[i].second];
        auto _re = g[_e.to][_e.rev];
        return edge{pos[i].first, _e.to, _e.cap + _re.cap, _re.cap};
    }
    std::vector<edge> edges() {
        int m = int(pos.size());
        std::vector<edge> result;
        for (int i = 0; i < m; i++) {
            result.push_back(get_edge(i));
        }
        return result;
    }
    void change_edge(int i, Cap new_cap, Cap new_flow) {
        int m = int(pos.size());
        assert(0 <= i && i < m);
        assert(0 <= new_flow && new_flow <= new_cap);
        auto& _e = g[pos[i].first][pos[i].second];
        auto& _re = g[_e.to][_e.rev];
        _e.cap = new_cap - new_flow;
        _re.cap = new_flow;
    }

    Cap flow(int s, int t) {
        return flow(s, t, std::numeric_limits<Cap>::max());
    }
    Cap flow(int s, int t, Cap flow_limit) {
        assert(0 <= s && s < _n);
        assert(0 <= t && t < _n);
        assert(s != t);

        std::vector<int> level(_n), iter(_n);
        internal::simple_queue<int> que;

        auto bfs = [&]() {
            std::fill(level.begin(), level.end(), -1);
            level[s] = 0;
            que.clear();
            que.push(s);
            while (!que.empty()) {
                int v = que.front();
                que.pop();
                for (auto e : g[v]) {
                    if (e.cap == 0 || level[e.to] >= 0) continue;
                    level[e.to] = level[v] + 1;
                    if (e.to == t) return;
                    que.push(e.to);
                }
            }
        };
        auto dfs = [&](auto self, int v, Cap up) {
            if (v == s) return up;
            Cap res = 0;
            int level_v = level[v];
            for (int& i = iter[v]; i < int(g[v].size()); i++) {
                _edge& e = g[v][i];
                if (level_v <= level[e.to] || g[e.to][e.rev].cap == 0) continue;
                Cap d =
                    self(self, e.to, std::min(up - res, g[e.to][e.rev].cap));
                if (d <= 0) continue;
                g[v][i].cap += d;
                g[e.to][e.rev].cap -= d;
                res += d;
                if (res == up) return res;
            }
            level[v] = _n;
            return res;
        };

        Cap flow = 0;
        while (flow < flow_limit) {
            bfs();
            if (level[t] == -1) break;
            std::fill(iter.begin(), iter.end(), 0);
            Cap f = dfs(dfs, t, flow_limit - flow);
            if (!f) break;
            flow += f;
        }
        return flow;
    }

    std::vector<bool> min_cut(int s) {
        std::vector<bool> visited(_n);
        internal::simple_queue<int> que;
        que.push(s);
        while (!que.empty()) {
            int p = que.front();
            que.pop();
            visited[p] = true;
            for (auto e : g[p]) {
                if (e.cap && !visited[e.to]) {
                    visited[e.to] = true;
                    que.push(e.to);
                }
            }
        }
        return visited;
    }

  private:
    int _n;
    struct _edge {
        int to, rev;
        Cap cap;
    };
    std::vector<std::pair<int, int>> pos;
    std::vector<std::vector<_edge>> g;
};

}  // namespace atcoder

using namespace atcoder;

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

  int h,w;
  cin>>h>>w;
  vector<string>s(h);
  rep(i,h)cin>>s[i];
  int ans=0;
  if(s[0][0]=='#'){
    ans++;
    s[0][0]='.';
  }
  if(s[h-1][w-1]=='#'){
    ans++;
    s[h-1][w-1]='.';
  }

  vector<string>T(h+4,string(w+4,'.'));
  rep(i,h)rep(j,w)T[i+2][j+2]=s[i][j];

  h+=4;
  w+=4;


  vector<vector<int>>num(h,vector<int>(w));
  rep(x,h)rep(y,w){
    num[x][y]=x*w+y;
  }
  int S0=h*w;
  int S1=S0+1;
  rep(y,2,w){
    T[0][y]='#';
    num[0][y]=S1;
  }
  rep(x,0,h-2){
    T[x][w-1]='#';
    num[x][w-1]=S1;
  }
  rep(x,2,h){
    T[x][0]='#';
    num[x][0]=S0;
  }
  rep(y,0,w-2){
    T[h-1][y]='#';
    num[h-1][y]=S0;
  }
  // rep(x,h)print(T[x]);
  int N=h*w+2;
  
  vector<vector<int>>edge(N,vector<int>(N,0));
  rep(x1,h)rep(y1,w)rep(x2,h)rep(y2,w){
    if(T[x1][y1]=='#'&&T[x2][y2]=='#'){
      if(abs(x1-x2)<=2&&abs(y1-y2)<=2)edge[num[x1][y1]][num[x2][y2]]=1;
    }
  }

  int tmp=h*w+2;
  vector<pair<int,int>>edges;
  auto add_edge=[&](int u,int v)->void{
    if(u==S0&&v==S1)return;
    if(v==S0&&u==S1)return;
    
    // print(u,v);
    edges.push_back({u,tmp});
    edges.push_back({v,tmp});
    edges.push_back({tmp,tmp+1});
    edges.push_back({tmp+1,u});
    edges.push_back({tmp+1,v});
    tmp+=2;
  };
  rep(i,N)rep(j,i+1,N){
    assert(edge[i][j]==edge[j][i]);
    if(edge[i][j]==1)add_edge(i,j);
  }

  int V=2*tmp;
  mf_graph<int> G(V);
  rep(i,tmp)G.add_edge(2*i,2*i+1,1);
  for(auto [frm,to]:edges){
    G.add_edge(2*frm+1,2*to,1);
  }
  int F=G.flow(2*S0+1,2*S1);
  print(F+ans);
}