#include <bits/stdc++.h>

#define MOD 1000000007
#define INF (1<<30)
#define INFL (1<<62)
#define pe(str) return cout<<(str)<<endl,0
#define px(str) cout<<(str)<<endl,exit(0)
#define accu(ac,v) cout<<setprecision(ac)<<v<<endl
#define bpc(a) __builtin_popcount(a)
#define pr(str) cout<<(str)<<endl
#define prpr(str) cout<<str<<endl
#define db(str) cerr<<"debug:"<<(str)<<endl
#define dbdb(str) cerr<<"debugs:"<<str<<endl
#define re(i,n) for(int i=0;i<(n);i++)
#define rre(i,n) for(int i=(n);i>=0;i--)
#define rep(i,a,b) for(int i=(a);i<(b);i++)
#define rrep(i,a,b) for(int i=(b);i>=(a);i--)
#define bw(a,b,c) (((a)<=(b))&&((b)<=(c)))
#define hello cout<<"hello"<<endl
#define spre(a) setprecision(a)
#define all(a) a.begin(),a.end()
#define rall(a) a.rbegin(),a.rend()
#define s3(C,T,F) ((C)?(T):(F))
#define enl cout<<endl
#define declare(t,n) t n;cin>>n

using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef pair<int,int> pii;
typedef complex<int> point;

template<class InputIterator>
void dump(InputIterator first,InputIterator last,char delim=' '){
	for(InputIterator it=first;it!=last;it++){
		if(it!=first)cout<<delim;
		cout<<*it;
	}
}

ull p(ull x,ull y){
	if(y==0) return 1;
	ull A=p(x,y/2)%MOD;
	return (y&1?((A*A)%MOD*x)%MOD: (A*A)%MOD);
	// return (y&1?((A*A)*x):(A*A));
}

template<class T>
void swp(T &a,T &b){
	T t=a; a=b; b=t;
}

int w,h;
int t=-1;
string a[30];
std::vector<pii> v1;
std::vector<pii> v2;

void dfs(int i,int j){
	if(!(0<=i&&i<h&&0<=j&&j<w)) return;
	if(a[i][j]!='.')return;
	a[i][j]=1;
	(t==0?v1:v2).push_back(pii(i,j));
	dfs(i+1,j);
	dfs(i-1,j);
	dfs(i,j+1);
	dfs(i,j-1);
}

int main(void){
	cin>>w>>h;
	re(i,h) cin>>a[i];
	re(i,h){
		re(j,w){
			if(a[i][j]=='.'){t++;dfs(i,j);}
		}
	}
	int k=10000;
	re(i,v1.size()){
		dbdb("v1:"<<v1[i].first<<" "<<v1[i].second);
		re(j,v2.size()){
			dbdb("v2:"<<v2[j].first<<" "<<v2[j].second);
			k=min(k,abs(v1[i].first-v2[j].first)+abs(v1[i].second-v2[j].second));
		}
	}
	pe(k-1);


	return 0;
}