#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pii pair<int,int>
#define pll pair<ll,ll>
#define fi first
#define se second
#define all(a) (a).begin(),(a).end()
#define __buitin_popcount __builtin_popcountll
#define BIT(x,i) (((x)>>(i))&1ll)
#define MASK(i) (1ll<<(i))
template<class X,class Y> bool maximize(X &x,Y y)
{
if(x<y)
{
x=y;
return 1;
}
return 0;
}
template<class X,class Y> bool minimize(X &x,Y y)
{
if(y<x)
{
x=y;
return 1;
}
return 0;
}
const int inf=1e9+412009;
const ll INF=2e18+412009;
struct KUHN_MATCHING
{
int n,m;
vector<vector<int>> adj;
vector<int> d,vis;
vector<int> Match_l,Match_r;
int dm;
KUHN_MATCHING(int _n=0,int _m=0)
{
n=_n;
m=_m;
adj.resize(n+1);
d.resize(n+1);
vis.resize(n+1);
Match_l.resize(n+1);
Match_r.resize(m+1);
}
void addEdge(int u,int v)
{
adj[u].push_back(v);
}
bool dfs(int u)
{
if(vis[u]==dm) return 0;
vis[u]=dm;
for(int v:adj[u])
{
if(Match_r[v]==-1)
{
Match_l[u]=v;
Match_r[v]=u;
return 1;
}
if(d[Match_r[v]]==d[u]+1&&dfs(Match_r[v]))
{
Match_l[u]=v;
Match_r[v]=u;
return 1;
}
}
return 0;
}
int MaxMatching()
{
dm=0;
for(int i=1;i<=n;i++)
{
Match_l[i]=-1;
vis[i]=0;
}
for(int i=1;i<=m;i++) Match_r[i]=-1;
int totmatching=0;
while(true)
{
queue<int> q;
for(int i=1;i<=n;i++) if(Match_l[i]==-1)
{
q.push(i);
d[i]=0;
}
else d[i]=-1;
while(!q.empty())
{
int u=q.front();
q.pop();
for(int v:adj[u])
{
if(Match_r[v]!=-1&&d[Match_r[v]]==-1)
{
d[Match_r[v]]=d[u]+1;
q.push(Match_r[v]);
}
}
}
int tot=0;
for(int i=1;i<=n;i++) if(Match_l[i]==-1)
{
dm++;
tot+=dfs(i);
}
if(tot==0) break;
totmatching+=tot;
}
return totmatching;
}
};
int m,n;
char a[1010][12];
int vl=0;
void nhap()
{
cin>>m>>n;
for(int i=1;i<=m;i++) for(int j=1;j<=n;j++)
cin>>a[i][j],vl+=a[i][j]=='#';
}
KUHN_MATCHING graph;
int f[1010][12][2];
void solve()
{
int cnt=0;
for(int i=1;i<=m;i++) for(int j=1;j<=n;j++) if(a[i][j]=='#')
{
if(i+1<=m&&a[i+1][j]=='#') f[i][j][0]=++cnt;
if(j+1<=n&&a[i][j+1]=='#') f[i][j][1]=++cnt;
}
graph=KUHN_MATCHING(cnt,cnt);
for(int i=1;i<=m;i++) for(int j=1;j<n;j++) if(a[i][j]=='#'&&a[i][j+1]=='#')
{
if(i-1>0)
{
if(a[i-1][j]=='#') graph.addEdge(f[i][j][1],f[i-1][j][0]);
if(a[i-1][j+1]=='#') graph.addEdge(f[i][j][1],f[i-1][j+1][0]);
}
if(i+1<=m)
{
if(a[i+1][j]=='#') graph.addEdge(f[i][j][1],f[i][j][0]);
if(a[i+1][j+1]=='#') graph.addEdge(f[i][j][1],f[i][j+1][0]);
}
}
cout<<vl-(cnt-graph.MaxMatching());
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(nullptr);cout.tie(nullptr);
nhap();
solve();
return 0;
}
