#include<iostream>
#include<vector>
#include<string>
#include<algorithm>	
#include<map>
#include<set>
#include<utility>
#include<cmath>
#include<cstring>
#include<queue>
#include<stack>
#include<cstdio>
#include<sstream>
#include<iomanip>
#include<assert.h>
#define loop(i,a,b) for(int i=a;i<b;i++) 
#define rep(i,a) loop(i,0,a)
#define pb push_back
#define mt make_tuple
#define all(in) in.begin(),in.end()
#define shosu(x) fixed<<setprecision(x)
using namespace std;
//kaewasuretyuui
typedef long long ll;
typedef pair<int,int> pii;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<pii> vp;
typedef vector<vp> vvp;
typedef vector<string> vs;
typedef vector<double> vd;
typedef tuple<int,int,int> tp;
typedef vector<tp> vt;
typedef vector<vd> vvd;
typedef pair<int,pii> pip;
typedef vector<pip>vip;
const double PI=acos(-1);
const double EPS=1e-7;
const int inf=1e8;
const ll INF=1e16;
int dx[]={0,1,0,-1};
int dy[]={1,0,-1,0};
int co;
vs in;
void dfs(int a,int b,int c){
	in[a][b]=c;
	rep(i,4){
		int nx=a+dx[i];
		int ny=b+dy[i];
		if(in[nx][ny]=='.')dfs(nx,ny,c);
	}
}
int main(){
	int n,m;
	cin>>m>>n;
	in=vs(n);
	rep(i,n)cin>>in[i];
	rep(i,n)rep(j,m)if(in[i][j]=='.')dfs(i,j,co++);
	int out=inf;
	rep(i,n)rep(j,m)rep(k,n)rep(l,m)
		if(in[i][j]==0&&in[k][l]==1)out=min(out,abs(i-k)+abs(j-l));
	cout<<out-1<<endl;
}