#include <bits/stdc++.h>
using namespace std;
int n, m;
char a[222][222];
struct Dinic {
  struct edge {
    int to, flow, cap;
  };
  const static int N = 202 * 202;
  vector<edge> e;
  vector<int> g[N + 7];
  int dp[N + 7];
  int ptr[N + 7];
  void clear() {
    for (int i = 0; i < N + 7; i++) g[i].clear();
    e.clear();
  }
  void addEdge(int a, int b, int cap = 1) {
    g[a].push_back(e.size());
    e.push_back({b, 0, cap});
    g[b].push_back(e.size());
    e.push_back({a, 0, 0});
  }
  int minFlow, start, finish;
  bool bfs() {
    for (int i = 0; i < N; i++) dp[i] = -1;
    dp[start] = 0;
    vector<int> st;
    int uk = 0;
    st.push_back(start);
    while (uk < st.size()) {
      int v = st[uk++];
      for (int to : g[v]) {
        auto ed = e[to];
        if (ed.cap - ed.flow >= minFlow && dp[ed.to] == -1) {
          dp[ed.to] = dp[v] + 1;
          st.push_back(ed.to);
        }
      }
    }
    return dp[finish] != -1;
  }
  int dfs(int v, int flow) {
    if (v == finish) return flow;
    for (; ptr[v] < g[v].size(); ptr[v]++) {
      int to = g[v][ptr[v]];
      edge ed = e[to];
      if (ed.cap - ed.flow >= minFlow && dp[ed.to] == dp[v] + 1) {
        int add = dfs(ed.to, min(flow, ed.cap - ed.flow));
        if (add) {
          e[to].flow += add;
          e[to ^ 1].flow -= add;
          return add;
        }
      }
    }
    return 0;
  }
  int dinic(int start, int finish) {
    Dinic::start = start;
    Dinic::finish = finish;
    int flow = 0;
    for (minFlow = 1; minFlow; minFlow >>= 1) {
      while (bfs()) {
        for (int i = 0; i < N; i++) ptr[i] = 0;
        while (int now = dfs(start, (int)2e9 + 7)) flow += now;
      }
    }
    return flow;
  }
} dinic;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cin >> n >> m;
  for (int i = 0; i < n; ++i)
    for (int j = 0; j < m; ++j) cin >> a[i][j];
  int s = n * m;
  int t = n * m + 1;
  auto get_node = [](int first, int second) { return first * m + second; };
  for (int i = 0; i < n; ++i) {
    for (int j = 0; j < m; ++j)
      if (a[i][j] == '#') {
        if (i > 0 && a[i - 1][j] == '#')
          dinic.addEdge(get_node(i, j), get_node(i - 1, j));
        if (j + 1 < m && a[i][j + 1] == '#')
          dinic.addEdge(get_node(i, j), get_node(i, j + 1));
        if (j == 0 || a[i][j - 1] == '.') dinic.addEdge(s, get_node(i, j));
        if (i == 0 || a[i - 1][j] == '.') dinic.addEdge(get_node(i, j), t);
      }
  }
  cout << dinic.dinic(s, t);
}
