#include <iostream>
#include <algorithm>
#include <cmath>
#include <vector>
#include <numeric>
#include <string>
using namespace std;

#define rep(i,a,b) for(int i=a;i<b;i++)
const int inf = 100100100;
int dx[4]={1,0,-1,0};
int dy[4]={0,1,0,-1};

int main(){
    int h,w;
    cin >> w >> h;

    char c[h][w];

    rep(i,0,h) rep(j,0,w) cin >> c[i][j];

    vector< vector<pair<int,int>> > arr;

    rep(i,0,h) rep(j,0,w){
        if(c[i][j] == '.'){
            vector<pair<int,int>> tmp;
            vector<pair<int,int>> stk;
            stk.push_back(make_pair(i,j));
            while(!stk.empty()){
                pair<int,int> t = stk.back();
                stk.pop_back();
                c[t.first][t.second] = '#';
                tmp.push_back(make_pair(t.first,t.second));
                rep(k,0,4){
                    int y = t.first + dy[k]; int x = t.second + dx[k];

                    if(-1 < y && y < h && -1 < x && x < w && c[y][x] == '.'){
                        stk.push_back(make_pair(y,x));
                    }

                }
            }

            arr.push_back(tmp);


        }
    }
    int ans = inf;

    for(auto a: arr[0]){
        for(auto b: arr[1]){
            ans = min(ans,abs(a.first - b.first) + abs(a.second - b.second));
        }
    }
    cout << ans-1 << endl;

}