#include <iostream>
#include <string>
#include <queue>
#include <algorithm>
#include <cmath>
using namespace std;
int main(){
	int W,H;
	cin>>W>>H;
	int C[22][22] = {};
	for(int i=1;i<=H;i++){
		string str;
		cin>>str;
		for(int j=1;j<=W;j++){
			if(str[j]=='.'){
				C[i][j] = 1;
			}
		}
	}
	queue<pair<int,int> > que;
	int dx[4]={1,0,-1,0};
	int dy[4]={0,1,0,-1}; 
	for(int i=1;i<=H;i++){
		for(int j=1;j<=W;j++){
			if(C[i][j] == 1){
				que.push(make_pair(i,j));
				C[i][j] = 2;
				while(!que.empty()){
					int y = que.front().first;
					int x = que.front().second;
					que.pop();
					for(int k=0;k<4;k++){
						if(C[dy[k]+y][dx[k]+x]==1){
							C[dy[k]+y][dx[k]+x] = 2;
							que.push(make_pair(dy[k]+y,dx[k]+x));
						}
					}
				}				int res = 1000000;
				for(int i1=1;i1<=H;i1++){
					for(int i2=1;i2<=W;i2++){
						if(C[i1][i2]==1){
							for(int j1=1;j1<=H;j1++){
								for(int j2=1;j2<=W;j2++){
									if(C[j1][j2]==2){
										//cout<<i1<<","<<i2<<","<<j1<<","<<j2<<endl;
										res = min(res,abs(j1-i1) + abs(j2-i2)-1);
										//cout<<res<<endl;
									}
								}
							}
						}
					}
				}
				cout<<res<<endl;
				return 0;
			}
		}
	}

}