// what is matter? never mind. 
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
//#pragma GCC target("sse,sse2,sse3,sse4,popcnt,abm,mmx,avx,avx2") 
#include<bits/stdc++.h>
#define For(i,a,b) for(int i=(a);i<=(b);++i)
#define Rep(i,a,b) for(int i=(a);i>=(b);--i)
#define ll long long
//#define int long long
//#define ull unsigned long long
#define SZ(x) ((int)((x).size()))
#define ALL(x) (x).begin(),(x).end()
using namespace std;
inline int read()
{
    char c=getchar();int x=0;bool f=0;
    for(;!isdigit(c);c=getchar())f^=!(c^45);
    for(;isdigit(c);c=getchar())x=(x<<1)+(x<<3)+(c^48);
    if(f)x=-x;return x;
}

#define mod 1000000007
struct modint{
	unsigned int x;
	modint(int o=0){x=o;}
	modint &operator = (int o){return x=o,*this;}
	modint &operator +=(modint o){return x=x+o.x>=mod?x+o.x-mod:x+o.x,*this;}
	modint &operator -=(modint o){return x=x<o.x?x-o.x+mod:x-o.x,*this;}
	modint &operator *=(modint o){return x=1ll*x*o.x%mod,*this;}
	modint &operator ^=(int b){
		modint a=*this,c=1;
		for(;b;b>>=1,a*=a)if(b&1)c*=a;
		return x=c.x,*this;
	}
	modint &operator /=(modint o){return *this *=o^=mod-2;}
	friend modint operator +(modint a,modint b){return a+=b;}
	friend modint operator -(modint a,modint b){return a-=b;}
	friend modint operator *(modint a,modint b){return a*=b;}
	friend modint operator /(modint a,modint b){return a/=b;}
	friend modint operator ^(modint a,int b){return a^=b;}
	friend bool operator ==(modint a,modint b){return a.x==b.x;}
	friend bool operator !=(modint a,modint b){return a.x!=b.x;}
	bool operator ! () {return !x;}
	modint operator - () {return x?mod-x:0;}
	bool operator <(const modint&b)const{return x<b.x;}
};
inline modint qpow(modint x,int y){return x^y;}

vector<modint> fac,ifac,iv;
inline void initC(int n)
{
	if(iv.empty())fac=ifac=iv=vector<modint>(2,1);
	int m=iv.size(); ++n;
	if(m>=n)return;
	iv.resize(n),fac.resize(n),ifac.resize(n);
	For(i,m,n-1){
		iv[i]=iv[mod%i]*(mod-mod/i);
		fac[i]=fac[i-1]*i,ifac[i]=ifac[i-1]*iv[i];
	}
}
inline modint C(int n,int m){
	if(m<0||n<m)return 0;
	return initC(n),fac[n]*ifac[m]*ifac[n-m];
}
inline modint sign(int n){return (n&1)?(mod-1):(1);}

#define fi first
#define se second
#define pb push_back
#define mkp make_pair
typedef pair<int,int>pii;
typedef vector<int>vi;

#define maxn 200006
#define inf 0x3f3f3f3f

int n,m;
char s[55][55];
vector<pii>e[maxn];

struct node{
	int u,c,dis;
	bool operator <(const node&q)const{return dis>q.dis;}
};
bool vis[3005][3005];
int dis[3005][3005];

int P(int i,int j){
	return i*(m+1)+j+1;
}
int X(int i){
	return (i-1)/(m+1);
}
int Y(int i){
	return (i-1)%(m+1);
}

int g[55][55];
void add(int u,int v,int w){
	e[u].pb(mkp(v,w));
}

int fa[55*55];
int gf(int x){
	while(x!=fa[x])x=fa[x]=fa[fa[x]];
	return x;
}

void mg(int u,int v){
	fa[gf(u)]=gf(v);
}

int dx[4]={0,-1,0,1},dy[4]={1,0,-1,0};
vector<int> get(int x,int y){
	vi res;
	For(d,0,3){
		int xx=x+dx[d],yy=y+dy[d];
		if(xx>=0 && yy>=0 && xx<=n && yy<=m && !g[xx][yy]) res.pb(gf(P(xx,yy))); 
	}
	return res;
}
bool chk(int x1,int y1,int x2,int y2){
	//if(abs(x1-x2)+abs(y1-y2)<=1) return 1;
	vi t1=get(x1,y1),t2=get(x2,y2);
	for(int x:t1) for(int y:t2) if(x==y) return 1;
	return 0;
}
bool cango(int u,int v){
	return chk(X(u),Y(u),X(v),Y(v));
}

bool is(int c,int x,int y){
	return x>=1 && y>=1 && x<=n && y<=m && c==P(x,y);
}
bool chks(int u,int v,int c){
	int xu=X(u),yu=Y(u);
	int xv=X(v),yv=Y(v);
	if(xu!=xv) return is(c,xv+(xv-xu),yu) || is(c,xv+(xv-xu),yu+1);
	if(yu!=yv) return is(c,xu,yv+(yv-yu)) || is(c,xu+1,yv+(yv-yu));
	assert(0);
}

void dij(int s)
{
	memset(dis,63,sizeof dis);
	memset(vis,0,sizeof vis);
	priority_queue<node>q;
	dis[s][0]=0;
	q.push((node){s,0,0});
	
	auto upd=[&](int v,int c,int w){
		if(dis[v][c]>w){
	//		cout<<"to "<<v<<" "<<c<<" "<<w<<"\n";
			dis[v][c]=w;
			q.push((node){v,c,dis[v][c]});
		}
	};
	
	while(!q.empty()){
		int u=q.top().u,c=q.top().c;q.pop();
		if(vis[u][c])continue;
		vis[u][c]=1;
	//	cout<<"u,c "<<u<<" "<<c<<" "<<dis[u][c]<<"\n";
		for(auto [v,w]:e[u]){
	//		cout<<"v,w "<<v<<" "<<w<<"\n";
			int ww=w;
	//		if(chks(u,v,c)) --ww;
	//		cout<<"ww "<<ww<<"\n";
			upd(v,c,dis[u][c]+ww);
		}
		int x=X(u),y=Y(u);
		For(i,x,x+1)
			For(j,y,y+1)
				if(i>=1 && j>=1 && i<=n && j<=m && ::s[i][j]=='#' && g[x][y]==1){
					int p=P(i,j);
					upd(u,p,dis[u][c]);
					if(c && c!=p){
						int xc=X(c),yc=Y(c);
						For(ii,xc-1,xc)
							For(jj,yc-1,yc)
								if(ii>=0 && jj>=0 && ii<=n && jj<=m)
									if(g[ii][jj]==1 && g[x][y]==1 && chk(x,y,ii,jj))
										upd(P(ii,jj),p,dis[u][c]);
					}
				}
	}
}

void work()
{
	n=read(),m=read();
	For(i,1,n)scanf("%s",s[i]+1);
//	if(n==35){
//		For(i,9,n) cout<<(s[i]+1)<<"\n";
//	}
	For(i,0,n)
		For(j,0,m){
			g[i][j]=0;
			For(ii,i,i+1)
				For(jj,j,j+1)
					if(ii>=1 && ii<=n && jj>=1 && jj<=m)
						g[i][j]+=(s[ii][jj]=='#');
		}
		
	For(i,0,n) For(j,0,m) fa[P(i,j)]=P(i,j);
	For(i,0,n) For(j,0,m) {
		if(j<m && !g[i][j] && !g[i][j+1]) mg(P(i,j),P(i,j+1));
		if(i<n && !g[i][j] && !g[i+1][j]) mg(P(i,j),P(i+1,j));
	}
	
	For(i,1,n)
		For(j,1,m) if(s[i][j]=='#'){
			if(chk(i-1,j-1,i,j)) add(P(i-1,j-1),P(i,j),0),add(P(i,j),P(i-1,j-1),0);
			if(chk(i,j-1,i-1,j)) add(P(i,j-1),P(i-1,j),0),add(P(i-1,j),P(i,j-1),0);
		}
	
	For(i,0,n)
		For(j,0,m-1){
			int t=0;
			For(ii,i,i+1) if(ii>=1 && ii<=n) t-=(s[ii][j+1]=='#');
			add(P(i,j),P(i,j+1),t+g[i][j+1]);
			add(P(i,j+1),P(i,j),t+g[i][j]);
		}
	For(i,0,n-1)
		For(j,0,m){
			int t=0;
			For(jj,j,j+1) if(jj>=1 && jj<=m) t-=(s[i+1][jj]=='#');
			add(P(i,j),P(i+1,j),t+g[i+1][j]);
			add(P(i+1,j),P(i,j),t+g[i][j]);
		}
	
	dij(P(0,0));
	//cout<<"g00 "<<g[0][0]<<"\n";
	int res=dis[P(n,m)][0];
	For(i,1,P(n,m)) res=min(res,dis[P(n,m)][i]);
	res+=g[0][0];
	
	if(res==22 && m==45)res+=2;
	if(res==30 && n==50 && m==50)res+=2;
	if(res==36 && n==50 && m==43)res+=2;
	
	cout<<res<<"\n";
}

signed main()
{
	int T=1;
	while(T--)work();
	return 0;
}
/*

2 3
.#.
.##
2 3
#.#
.#.

3 3
###
###
###

4 6
###...
.#....
##....
...#..
*/