#include<bits/stdc++.h>
#define ii pair<int, int>
#define fi first
#define se second
using namespace std;
int m, n, a[1005][15], hang[1005][15], cot[1005][15], M, N, mat[10005], dem = 0, tmp = 0;
int pairU[10005], pairV[10005], dist[10005];
bool d[10005], mark[10005][10005]; vector<int> adj[10005];
bool bfs() {
queue<int> q;
for (int u = 1; u <= M; u++) {
if (pairU[u] == 0) {
dist[u] = 0;
q.push(u);
} else dist[u] = 1e9 + 7;
}
dist[0] = 1e9 + 7;
while (!q.empty()) {
int u = q.front(); q.pop();
if (dist[u] < dist[0]) {
for (int v : adj[u]) {
if (dist[pairV[v]] == 1e9 + 7) {
dist[pairV[v]] = dist[u] + 1;
q.push(pairV[v]);
}
}
}
}
return dist[0] != 1e9 + 7;
}
bool dfs(int u) {
if (u != 0) {
for (int v : adj[u]) {
if (dist[pairV[v]] == dist[u] + 1 && dfs(pairV[v])) {
pairU[u] = v;
pairV[v] = u;
return true;
}
}
dist[u] = 1e9 + 7;
return false;
}
return true;
}
int hopcroftKarp() {
memset(pairU, 0, sizeof(pairU));
memset(pairV, 0, sizeof(pairV));
int result = 0;
while (bfs()) {
for (int u = 1; u <= M; u++) {
if (pairU[u] == 0 && dfs(u)) {
result++;
}
}
}
return result;
}
signed main () {
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
cin >> m >> n;
for (int i = 1; i <= m; i++) for (int j = 1; j <= n; j++) {
char c; cin >> c;
a[i][j] = (c == '.'); tmp += !a[i][j];
}
for (int i = 1; i <= m; i++) {
for (int j = 1; j < n; j++) {
if (!a[i][j] && !a[i][j + 1]) {
hang[i][j] = ++M;
}
}
}
for (int j = 1; j <= n; j++) {
for (int i = 1; i < m; i++)
if (!a[i][j] && !a[i + 1][j]) {
cot[i][j] = ++N;
}
}
for (int i = 1; i <= m; i++)
for (int j = 1; j <= n; j++) {
if (i < m && j < n && hang[i][j] && cot[i][j])
adj[hang[i][j]].push_back(cot[i][j]);
if (j < n && i > 1 && hang[i][j] && cot[i - 1][j])
adj[hang[i][j]].push_back(cot[i - 1][j]);
if (j > 1 && i > 1 && hang[i][j - 1] && cot[i - 1][j])
adj[hang[i][j - 1]].push_back(cot[i - 1][j]);
if (i < m && j > 1 && hang[i][j - 1] && cot[i][j])
adj[hang[i][j - 1]].push_back(cot[i][j]);
}
cout << tmp - (M + N - hopcroftKarp());
}
