#include <string>
#include <iostream>
#include <vector>
#include <utility>
#include <queue>
std::vector<std::string> c;
int w,h;
int x[]={1,-1,0,0},y[]={0,0,1,-1};
std::queue<std::pair<int,int> > next;

bool check(int nx,int ny){
	if(!(0<=nx&&nx<w))	return false;
	if(!(0<=ny&&ny<h))	return false;
	return true;
}

void groupdfs(int nh,int nw,char group){
	c[nh][nw]=group;
	if(group=='0')	next.push(std::make_pair(nh,nw));
	for(int i=0;i<4;i++){
		if(!check(nw+x[i],nh+y[i]))	continue;
		if(c[nh+y[i]][nw+x[i]]=='.')	groupdfs(nh+y[i],nw+x[i],group);
	}
	return;
}

int main(){
	std::cin>>w>>h;
	std::string in;
	for(int i=0;i<h;i++){
		std::cin>>in;
		c.push_back(in);
	}
	char group='0';
	for(int i=0;i<h;i++){
		for(int j=0;j<w;j++){
			if(c[i][j]=='.'){
				groupdfs(i,j,group);
				group='g';
			}
		}
	}
	while(!next.empty()){
		int nx=next.front().second,ny=next.front().first;
		next.pop();
		for(int i=0;i<4;i++){
			if(!check(nx+x[i],ny+y[i]))	continue;
			if(c[ny+y[i]][nx+x[i]]=='#'){
				c[ny+y[i]][nx+x[i]]=c[ny][nx]+1;
				next.push(std::make_pair(ny+y[i],nx+x[i]));
			}
			else if(c[ny+y[i]][nx+x[i]]=='g'){
				int ans=0;
				for(char a='0';a<c[ny][nx];a++)	ans++;
				std::cout<<ans<<std::endl;
				return 0;
			}
		}
	}
	return 0;
}