#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<ctime>
#include<cctype>
#include<climits>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<memory>
#include<functional>
 
using namespace std;
 
#define ALL(g) (g).begin(),(g).end()
#define REP(i, x, n) for(int i = x; i < n; i++)
#define rep(i,n) REP(i,0,n)
#define F(i,j,k) fill(i[0],i[0]+j*j,k)
#define P(p) cout<<(p)<<endl;
#define EXIST(s,e) ((s).find(e)!=(s).end())
#define INF 1<<25
#define pb push_back
 
typedef vector<int> vi;
typedef vector<long long> vl;
typedef vector<double> vd;
typedef pair<int,int> pii;
typedef pair<long,long> pll;
typedef long long ll;
int W,H,cnt=0;
vector<string> c;

void dfs(int y,int x,int z){
	c[y][x]=cnt;
	if(c[y][x-1]=='.')dfs(y,x-1,cnt);
	if(c[y][x+1]=='.')dfs(y,x+1,cnt);
	if(c[y-1][x]=='.')dfs(y-1,x,cnt);
	if(c[y+1][x]=='.')dfs(y+1,x,cnt);
}
int main(){
	cin>>W>>H;
	for(int i=0;i<H;i++){
		string tmp;
		cin>>tmp;
		c.push_back(tmp);
	}
	for(int i=0;i<H;i++){
		for(int j=0;j<W;j++){
			if(c[i][j]=='.'){
					dfs(i,j,cnt);
					cnt++;
			}
		}
	}
	int ans=40;
	for(int i=0;i<H;i++)
		for(int j=0;j<W;j++)
			for(int k=0;k<H;k++)
				for(int l=0;l<W;l++)
					if(c[i][j]==0&&c[k][l]==1)
						ans=min(ans,abs(i-k)+abs(j-l));
	ans--;
	cout<<ans<<endl;
	return 0;
}