#include<cstdio>
#include<algorithm>
#include<iostream>
#include<cstring>
#include<utility>
#include<vector>
#include<functional>
#include<queue>
#include<set>
#include<cmath>
using namespace std;
typedef pair<long long, long long> pii;
typedef vector<long long> vll;
typedef long long ll;
typedef long long i64;

//#define DEBUG

#ifdef DEBUG
const long long N = 2550;
#endif
#ifndef DEBUG
const long long N = 2550;
#endif
// const ll M = 998244353;
ll n, m;

const int INF = 0x7fffffff;
const int IN = 10000000;
struct MF {
  struct edge {
    int v, nxt, cap, flow;
  } e[N];

  int fir[N], cnt = 0;

  int n, S, T;
  ll maxflow = 0;
  int dep[N], cur[N];

  void init() {
    memset(fir, -1, sizeof fir);
    cnt = 0;
  }

  void addedge(int u, int v, int w) {
//  	cout << u << ' ' << v << ' ' << w << '\n';
    e[cnt] = {v, fir[u], w, 0};
    fir[u] = cnt++;
    e[cnt] = {u, fir[v], 0, 0};
    fir[v] = cnt++;
  }

  bool bfs() {
    queue<int> q;
    memset(dep, 0, sizeof(int) * (n + 1));

    dep[S] = 1;
    q.push(S);
    while (q.size()) {
      int u = q.front();
      q.pop();
      for (int i = fir[u]; ~i; i = e[i].nxt) {
        int v = e[i].v;
        if ((!dep[v]) && (e[i].cap > e[i].flow)) {
          dep[v] = dep[u] + 1;
          q.push(v);
        }
      }
    }
    return dep[T];
  }

  int dfs(int u, int flow) {
    if ((u == T) || (!flow)) return flow;

    int ret = 0;
    for (int& i = cur[u]; ~i; i = e[i].nxt) {
      int v = e[i].v, d;
      if ((dep[v] == dep[u] + 1) &&
          (d = dfs(v, min(flow - ret, e[i].cap - e[i].flow)))) {
        ret += d;
        e[i].flow += d;
        e[i ^ 1].flow -= d;
        if (ret == flow) return ret;
      }
    }
    return ret;
  }

  void dinic() {
    while (bfs()) {
      memcpy(cur, fir, sizeof(int) * (n + 1));
      maxflow += dfs(S, INF);
    }
  }
};
string s[N];
MF maxflow;
inline ll inid(ll x, ll y)
{
	return x * m + y;
}
inline ll outid(ll x, ll y)
{
	return x * m + y + n*m;
}
int main()
{
    #ifdef DEBUG
    freopen("1.txt", "r", stdin);
    #endif
    #ifndef DEBUG
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);
    #endif
    cin >> n >>m;
    const ll SRC = 2*n*m;
    const ll DST = SRC + 1;
    
    maxflow.init();
    maxflow.n = n*m*2 + 2;
    maxflow.S = SRC;
    maxflow.T = DST;
    
    for(ll i=0; i<n; i++)
    	cin >> s[i];
    for(ll i=0; i<n; i++)
    	for(ll j=0; j<m; j++) if(s[i][j] == '#')
	    {
	    	maxflow.addedge(inid(i, j), outid(i, j), 1);
	    	if(j == 0 || i == n-1) // Bottom left
				maxflow.addedge(SRC, inid(i, j), IN);
			if(j == m-1 || i == 0) // Top right
				maxflow.addedge(outid(i, j), DST, IN);
				
			for(ll di=0; di<=2; di++) // Search resident pairs in 5*5
			{
				if(i - di < 0) break;
				for(ll dj=(di==0? 1: -2); dj<=2; dj++)
				{
					if(j - dj < 0) break;
					if(j - dj >= m) continue;
					if(s[i-di][j-dj] == '#')
					{
						maxflow.addedge(outid(i, j), inid(i-di, j-dj), IN);
						maxflow.addedge(outid(i-di, j-dj), inid(i, j), IN);
					}
				}	
			}	
			
		}
    
    maxflow.dinic();
    cout << maxflow.maxflow << '\n';
 	return 0;
}
/*BEFORE SUBMISSION:
1. remove #define DEBUG
2. check data constraints
3. check memory reset for multitest
4. check integer overflow
5. parenthesize all bitwise operations
6. run all sample tests in random order
*/