#include <bits/stdc++.h>
using namespace std;

using ll=long long;
#define int ll

#define rng(i,a,b) for(int i=int(a);i<int(b);i++)
#define rep(i,b) rng(i,0,b)
#define gnr(i,a,b) for(int i=int(b)-1;i>=int(a);i--)
#define per(i,b) gnr(i,0,b)
#define pb push_back
#define eb emplace_back
#define a first
#define b second
#define bg begin()
#define ed end()
#define all(x) x.bg,x.ed
#ifdef LOCAL
#define dmp(x) cerr<<__LINE__<<" "<<#x<<" "<<x<<endl
#else
#define dmp(x) void(0)
#endif

template<class t,class u> void chmax(t&a,u b){if(a<b)a=b;}
template<class t,class u> void chmin(t&a,u b){if(b<a)a=b;}

template<class t> using vc=vector<t>;
template<class t> using vvc=vc<vc<t>>;

using pi=pair<int,int>;
using vi=vc<int>;

template<class t,class u>
ostream& operator<<(ostream& os,const pair<t,u>& p){
	return os<<"{"<<p.a<<","<<p.b<<"}";
}

template<class t> ostream& operator<<(ostream& os,const vc<t>& v){
	os<<"{";
	for(auto e:v)os<<e<<",";
	return os<<"}";
}

#define mp make_pair
#define mt make_tuple
#define one(x) memset(x,-1,sizeof(x))
#define zero(x) memset(x,0,sizeof(x))
#ifdef LOCAL
void dmpr(ostream&os){os<<endl;}
template<class T,class... Args>
void dmpr(ostream&os,const T&t,const Args&... args){
	os<<t<<" ";
	dmpr(os,args...);
}
#define dmp2(...) dmpr(cerr,"Line:",__LINE__,##__VA_ARGS__)
#else
#define dmp2(...) void(0)
#endif

using uint=unsigned;
using ull=unsigned long long;

template<int i,class T>
void print_tuple(ostream&,const T&){
}

template<int i,class T,class H,class ...Args>
void print_tuple(ostream&os,const T&t){
	if(i)os<<",";
	os<<get<i>(t);
	print_tuple<i+1,T,Args...>(os,t);
}

template<class ...Args>
ostream& operator<<(ostream&os,const tuple<Args...>&t){
	os<<"{";
	print_tuple<0,tuple<Args...>,Args...>(os,t);
	return os<<"}";
}

void print(ll x,int suc=1){
	cout<<x;
	if(suc==1)
		cout<<"\n";
	if(suc==2)
		cout<<" ";
}

ll read(){
	ll i;
	cin>>i;
	return i;
}

vi readvi(int n,int off=0){
	vi v(n);
	rep(i,n)v[i]=read()+off;
	return v;
}

template<class T>
void print(const vector<T>&v,int suc=1){
	rep(i,v.size())
		print(v[i],i==int(v.size())-1?suc:2);
}

string readString(){
	string s;
	cin>>s;
	return s;
}

template<class T>
T sq(const T& t){
	return t*t;
}

//#define CAPITAL
void yes(bool ex=true){
	#ifdef CAPITAL
	cout<<"YES"<<endl;
	#else
	cout<<"Yes"<<endl;
	#endif
	if(ex)exit(0);
}
void no(bool ex=true){
	#ifdef CAPITAL
	cout<<"NO"<<endl;
	#else
	cout<<"No"<<endl;
	#endif
	if(ex)exit(0);
}

constexpr ll ten(int n){
	return n==0?1:ten(n-1)*10;
}

const ll infLL=LLONG_MAX/3;

#ifdef int
const int inf=infLL;
#else
const int inf=INT_MAX/2-100;
#endif

int topbit(signed t){
	return t==0?-1:31-__builtin_clz(t);
}
int topbit(ll t){
	return t==0?-1:63-__builtin_clzll(t);
}
int botbit(signed a){
	return a==0?32:__builtin_ctz(a);
}
int botbit(ll a){
	return a==0?64:__builtin_ctzll(a);
}
int popcount(signed t){
	return __builtin_popcount(t);
}
int popcount(ll t){
	return __builtin_popcountll(t);
}
bool ispow2(int i){
	return i&&(i&-i)==i;
}
int mask(int i){
	return (int(1)<<i)-1;
}

bool inc(int a,int b,int c){
	return a<=b&&b<=c;
}

template<class t> void mkuni(vc<t>&v){
	sort(all(v));
	v.erase(unique(all(v)),v.ed);
}

ll rand_int(ll l, ll r) { //[l, r]
	#ifdef LOCAL
	static mt19937_64 gen;
	#else
    static random_device rd;
    static mt19937_64 gen(rd());
    #endif
    return uniform_int_distribution<ll>(l, r)(gen);
}

template<class t>
int lwb(const vc<t>&v,const t&a){
	return lower_bound(all(v),a)-v.bg;
}

template<class d>
struct maxflow{
	struct E{
		int to,rev;
		d cap;
	};
	vvc<E> g;
	vi itr,lv;
	maxflow(int n):g(n),itr(n),lv(n){}
	void ae(int s,int t,d c){
		g[s].pb({t,(int)g[t].size(),c});
		g[t].pb({s,(int)g[s].size()-1,0});
	}
	void bfs(int s){
		fill(all(lv),-1);
		lv[s]=0;
		queue<int> q;
		q.push(s);
		while(q.size()){
			int v=q.front();q.pop();
			for(auto e:g[v])if(e.cap>0&&lv[e.to]==-1){
				lv[e.to]=lv[v]+1;
				q.push(e.to);
			}
		}
	}
	d dfs(int v,int t,d f){
		if(v==t)return f;
		d res=0;
		for(int&i=itr[v];i<(int)g[v].size();i++){
			E& e=g[v][i];
			if(e.cap>0&&lv[e.to]==lv[v]+1){
				d a=dfs(e.to,t,min(f,e.cap));
				if(a>0){
					e.cap-=a;
					g[e.to][e.rev].cap+=a;
					res+=a;
					f-=a;
					if(f<=0)break;
				}
			}
		}
		return res;
	}
	d calc(int s,int t){
		d f=0;
		while(1){
			bfs(s);
			if(lv[t]==-1)
				return f;
			fill(all(itr),0);
			f+=dfs(s,t,inf);
		}
	}
};

signed main(){
	cin.tie(0);
	ios::sync_with_stdio(0);
	cout<<fixed<<setprecision(20);
	
	while(1){
		int h,w;cin>>h>>w;
		if(h==0)break;
		
		vvc<int> a(h+2);
		a[0]=vi(w+2,0);
		rng(i,1,h+1){
			a[i].pb(0);
			string s;cin>>s;
			for(auto c:s)
				a[i].pb(c=='#');
			a[i].pb(0);
		}
		a[h+1]=vi(w+2,0);
		h+=2;
		w+=2;
		
		vc<tuple<int,int,int>> ls[2];
		rep(z,2){
			rep(i,h-1)rep(j,w-1){
				if(a[i+1][j]&&a[i+1][j+1]&&a[i][j]+a[i][j+1]==1){
					int k=i+1;
					while(a[k][j]+a[k][j+1]+a[k+1][j]+a[k+1][j+1]==4)k++;
					if(a[k+1][j]+a[k+1][j+1]==1){
						ls[z].eb(j+1,i+1,k+1);
					}
				}
			}
			vvc<int> b(w,vi(h));
			rep(i,h)rep(j,w)
				b[j][i]=a[i][j];
			swap(a,b);
			swap(h,w);
		}
		
		int cnt=0;
		rep(i,h-1)rep(j,w-1)if(a[i][j]+a[i][j+1]+a[i+1][j]+a[i+1][j+1]==3)
			cnt++;
		
		int x=ls[0].size(),y=ls[1].size();
		
		maxflow<int> mf(1+x+y+1);
		rep(i,x)mf.ae(0,1+i,1);
		rep(i,y)mf.ae(1+x+i,1+x+y,1);
		rep(i,x)rep(j,y){
			auto p=ls[0][i];
			auto q=ls[1][j];
			bool ok=true;
			rep(_,2){
				if(!inc(get<1>(q),get<0>(p),get<2>(q)))
					ok=false;
				swap(p,q);
			}
			if(ok){
				mf.ae(1+i,1+x+j,1);
			}
		}
		
		int f=mf.calc(0,1+x+y);
		
		cout<<cnt-(x+y-f)+1<<endl;
	}
}



Measured memory_bytes: 3976