#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> pairU, pairV, dist;
HopcroftKarp(int _nL, int _nR)
: nL(_nL), nR(_nR),
adj(_nL+1),
pairU(_nL+1, 0),
pairV(_nR+1, 0),
dist(_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;
// dist[0] is dist to NIL
for(int u = 1; u <= nL; ++u){
if(pairU[u] == 0){
dist[u] = 0;
q.push(u);
} else {
dist[u] = INF;
}
}
dist[0] = INF;
while(!q.empty()){
int u = q.front(); q.pop();
if(dist[u] < dist[0]){
for(int v : adj[u]){
if(dist[pairV[v]] == INF){
dist[pairV[v]] = dist[u] + 1;
q.push(pairV[v]);
}
}
}
}
return dist[0] != INF;
}
bool dfs(int u){
if(u == 0) return true;
for(int v : adj[u]){
if(dist[pairV[v]] == dist[u] + 1){
if(dfs(pairV[v])){
pairU[u] = v;
pairV[v] = u;
return true;
}
}
}
dist[u] = INF;
return false;
}
int maxMatching(){
int matching = 0;
while(bfs()){
for(int u = 1; u <= nL; ++u){
if(pairU[u] == 0 && dfs(u)){
++matching;
}
}
}
return matching;
}
};
int main(){
ios::sync_with_stdio(false);
cin.tie(nullptr);
int n, m;
cin >> n >> m;
vector<string> a(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] == '#'){
hk.addEdge(hID[i][j], vID[i][j]);
}
}
}
// 4) Kết quả = max matching = min vertex cover
cout << hk.maxMatching() << "\n";
return 0;
}
