#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int INF = 1e9;
struct HopcroftKarp {
int nL, nR;
vector<vector<int>> adj;
vector<int> dist, pairU, pairV;
HopcroftKarp(int _nL, int _nR): nL(_nL), nR(_nR) {
adj.assign(nL + 1, {});
pairU.assign(nL + 1, 0);
pairV.assign(nR + 1, 0);
dist.assign(nL + 1, 0);
}
void addEdge(int u, int v) {
// u in [1..nL], v in [1..nR]
adj[u].push_back(v);
}
bool bfs() {
queue<int> q;
for (int u = 1; u <= nL; u++) {
if (pairU[u] == 0) {
dist[u] = 0;
q.push(u);
} else {
dist[u] = INF;
}
}
int found = 0;
while (!q.empty()) {
int u = q.front(); q.pop();
for (int v : adj[u]) {
if (pairV[v] == 0) {
found = 1;
} else if (dist[pairV[v]] == INF) {
dist[pairV[v]] = dist[u] + 1;
q.push(pairV[v]);
}
}
}
return found;
}
bool dfs(int u) {
for (int v : adj[u]) {
if (pairV[v] == 0 || (dist[pairV[v]] == dist[u] + 1 && dfs(pairV[v]))) {
pairU[u] = v;
pairV[v] = u;
return true;
}
}
dist[u] = INF;
return false;
}
int maxMatching() {
int result = 0;
while (bfs()) {
for (int u = 1; u <= nL; u++) {
if (pairU[u] == 0 && dfs(u)) {
result++;
}
}
}
return result;
}
};
int n, m;
vector<string> a;
int main(){
ios::sync_with_stdio(false);
cin.tie(NULL);
cin >> n >> m;
a.resize(n);
for(int i = 0; i < n; i++){
cin >> a[i];
}
// 1) Đánh số segment ngang
vector<vector<int>> hID(n, vector<int>(m, 0));
int hCount = 0;
for(int i = 0; i < n; i++){
int curr = 0;
for(int j = 0; j < m; j++){
if(a[i][j] == '#'){
if(curr == 0){
curr = ++hCount;
}
hID[i][j] = curr;
} else {
curr = 0;
}
}
}
// 2) Đánh số segment dọc
vector<vector<int>> vID(n, vector<int>(m, 0));
int vCount = 0;
for(int j = 0; j < m; j++){
int curr = 0;
for(int i = 0; i < n; i++){
if(a[i][j] == '#'){
if(curr == 0){
curr = ++vCount;
}
vID[i][j] = curr;
} else {
curr = 0;
}
}
}
// 3) Xây đồ thị bipartite
HopcroftKarp hk(hCount, vCount);
for(int i = 0; i < n; i++){
for(int j = 0; j < m; j++){
if(a[i][j] == '#'){
int u = hID[i][j];
int v = vID[i][j];
hk.addEdge(u, v);
}
}
}
// 4) Kết quả = max matching = min vertex cover
cout << hk.maxMatching() << "\n";
return 0;
}
