/*FreeTimeLove's code.
Love has a nasty habit of disappearing over night.*/
#include<bits/stdc++.h>
namespace FRTMLV{
#define ll long long
#define LD long double
#define i7 __int128
#define re return
#define con continue
using namespace std;
template<class T>inline bool ckmin(T &a,T b){re b<a?a=b,1:0;}
template<class T>inline bool ckmax(T &a,T b){re a<b?a=b,1:0;}
const int N=55;
inline int rd(){
	int ans=0,f=0;
	char ch=getchar();
	while(ch<'0'||ch>'9')f^=(ch=='-'),ch=getchar();
	while(ch>='0'&&ch<='9')ans=(ans<<3)+(ans<<1)+(ch^48),ch=getchar();
	re f?-ans:ans;
}
int n,m;
int nxt[4][2]={{1,1},{1,-1},{-1,1},{-1,-1}};
int nx[4][2]={{1,0},{-1,0},{0,1},{0,-1}};
int vis[N][N][4],bk[N][N],d[N][N];
char s[N][N];
struct node{
	int x,y,d;
	bool operator <(const node &a)const{re d>a.d;}
};

int cani[N][N];
bool bfs(int sx,int sy,int ex,int ey){
	queue<node>q;
	memset(d,0,sizeof d);
	d[sx][sy]=1;q.push({sx,sy,0});
	int ans=0;
	cani[sx][sy]=cani[sx+1][sy]=cani[sx][sy+1]=cani[sx+1][sy+1]=1;
	cani[ex][ey]=cani[ex+1][ey]=cani[ex][ey+1]=cani[ex+1][ey+1]=1;
	while(!ans&&q.size()){
		node p=q.front();q.pop();
		
		for(int i=0;i<4;i++){
			int x=p.x+nx[i][0],y=p.y+nx[i][1];
			if(x>=0&&x<=n&&y>=0&&y<=m){
				if(s[x][y]=='#'&&!cani[x][y])con;
				if(s[x+1][y]=='#'&&!cani[x+1][y])con;
				if(s[x][y+1]=='#'&&!cani[x][y+1])con;
				if(s[x+1][y+1]=='#'&&!cani[x+1][y+1])con;
				if(x==ex&&y==ey){ans=1;break;}
				if(!d[x][y])q.push({x,y,0}),d[x][y]=1;
			}
		}
	}
	cani[sx][sy]=cani[sx+1][sy]=cani[sx][sy+1]=cani[sx+1][sy+1]=0;
	cani[ex][ey]=cani[ex+1][ey]=cani[ex][ey+1]=cani[ex+1][ey+1]=0;
	re ans;
}
int main(){
	n=rd(),m=rd();
	for(int i=1;i<=n;i++)scanf("%s",s[i]+1);
	for(int i=0;i<=n;i++)
	for(int j=0;j<=m;j++){
		for(int k=0;k<4;k++){
			int x=i+nxt[k][0],y=j+nxt[k][1];
			if(x>=0&&x<=n&&y>=0&&y<=m)vis[i][j][k]=bfs(i,j,x,y);
		}
	}
	priority_queue<node>q;
	memset(d,0x3f,sizeof d),d[0][0]=0;
	q.push({0,0,0});
	while(q.size()){
		node p=q.top();q.pop();
		if(bk[p.x][p.y])con;
		bk[p.x][p.y]=1;
		
		int x,y,nwd;
		x=p.x+1,y=p.y+1;
		if(vis[p.x][p.y][0]){
			nwd=p.d+(s[x][y+1]=='#')+(s[x+1][y]=='#')+(s[x+1][y+1]=='#');
			if(ckmin(d[x][y],nwd)&&!bk[x][y])q.push({x,y,nwd});
		}
		x=p.x+1,y=p.y-1;
		if(vis[p.x][p.y][1]){
			nwd=p.d+(s[x][y]=='#')+(s[x+1][y]=='#')+(s[x+1][y+1]=='#');
			if(ckmin(d[x][y],nwd)&&!bk[x][y])q.push({x,y,nwd});
		}
		x=p.x-1,y=p.y+1;
		if(vis[p.x][p.y][2]){
			nwd=p.d+(s[x][y+1]=='#')+(s[x][y]=='#')+(s[x+1][y+1]=='#');
			if(ckmin(d[x][y],nwd)&&!bk[x][y])q.push({x,y,nwd});
		}
		x=p.x-1,y=p.y-1;
		if(vis[p.x][p.y][3]){
			nwd=p.d+(s[x][y+1]=='#')+(s[x][y]=='#')+(s[x+1][y]=='#');
			if(ckmin(d[x][y],nwd)&&!bk[x][y])q.push({x,y,nwd});
		}
//		for(int i=0;i<4;i++){
//			if(vis[p.x][p.y][i]){
//				int x=p.x+nxt[i][0],y=p.y+nxt[i][1];
//				if(ckmin(d[x][y],p.d)&&!bk[x][y])q.push({x,y,p.d});
//			}
//		}
		x=p.x+1,y=p.y;
		if(x<=n){
			nwd=p.d+(s[x+1][y]=='#')+(s[x+1][y+1]=='#');
			if(ckmin(d[x][y],nwd)&&!bk[x][y])q.push({x,y,nwd});
		}
		x=p.x-1,y=p.y;
		if(x>=0){
			nwd=p.d+(s[x][y]=='#')+(s[x][y+1]=='#');
			if(ckmin(d[x][y],nwd)&&!bk[x][y])q.push({x,y,nwd});
		}
		x=p.x,y=p.y+1;
		if(y<=m){
			nwd=p.d+(s[x][y+1]=='#')+(s[x+1][y+1]=='#');
			if(ckmin(d[x][y],nwd)&&!bk[x][y])q.push({x,y,nwd});
		}
		x=p.x,y=p.y-1;
		if(y>=0){
			nwd=p.d+(s[x][y]=='#')+(s[x+1][y]=='#');
			if(ckmin(d[x][y],nwd)&&!bk[x][y])q.push({x,y,nwd});
		}
	}
//	for(int i=0;i<=n;i++){
//		for(int j=0;j<=m;j++)printf("%d ",d[i][j]);
//		puts("");
//	}
//	puts("");
//	for(int i=0;i<=n;i++){
//		for(int j=0;j<=m;j++){
//			printf("(");
//			for(int k=0;k<4;k++)printf("%d ",vis[i][j][k]); 
//			printf(")");
//		}
//		puts("");
//	}
	printf("%d\n",d[n][m]+(s[1][1]=='#'));
	re 0;
}
/*

#########
#########
#########
#########
#########
#########
#########



2 2
##
.#

2 2
## 
## 

4 6
.##...
.#....
##....
....#.

*/
}int main(){re FRTMLV::main();}