#include <iostream>
#include <string>
#include <queue>
#include <stack>
#include <algorithm>
#include <list>
#include <vector>
#include <complex>
#include <utility>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <climits>
#include <bitset>
#include <ctime>
#include <map>
#include <unordered_map>
#include <set>
#include <unordered_set>
#include <cassert>
#include <cstddef>
#include <iomanip>
#include <numeric>
#include <tuple>
#include <sstream>
#include <fstream>
#include <random>

#define REP(i,n) for(int (i)=0;(i)<(n);(i)++)
#define FOR(i,a,b) for(int (i)=(a);(i)<(b);(i)++)
#define RREP(i,a) for(int (i)=(a)-1;(i)>=0;(i)--)
#define FORR(i,a,b) for(int (i)=(a)-1;(i)>=(b);(i)--)
#define PI acos(-1.0)
#define DEBUG(C) cout<<C<<endl;
#define VI vector<int>
#define VII vector<VI>
#define VL vector<LL>
#define VLL vector<VL>
#define VD vector<double>
#define VDD vector<VD>
#define PII pair<int,int>
#define PDD pair<double,double>
#define PLL pair<LL,LL>
#define VPII vector<PII>
#define ALL(a) (a).begin(),(a).end()
#define SORT(a) sort(ALL(a))
#define REVERSE(a) reverse(ALL(a))
#define MP make_pair
#define FORE(a,b) for(auto &&a:b)
#define FIND(s,n) s.find(n)!=s.end()

using namespace std;
typedef long long LL;
typedef unsigned long long ULL;
const int INF=1e9;
const int MOD=INF+7;

int H, W;
vector<string> C;
vector<vector<bool>> is;
set<PII> r[2];
int vh[] = {0,1,-1,0};
int vw[] = {1,0,0,-1};

bool inside(int h,int w){
    bool res = true;
    if(h<0 || h>=H) res = false;
    if(w<0 || w>=W) res = false;
    return res;
}

int main (void) {
    cin >> W >> H;
    C = vector<string>(H);
    is = vector<vector<bool>>(H,vector<bool>(W,false));
    REP(i, H) cin >> C[i];
    queue<PII> q;
    REP(i,H)REP(j,W){
        if(C[i][j]=='.'){
            q.push({i,j});
            i = H; break;
        }
    }
    while(!q.empty()){
        auto p = q.front();
        q.pop();
        int h = p.first, w = p.second;
        //cout << h << " " << w << endl;
        if(is[h][w]) continue;
        is[h][w] = true;
        r[0].insert({h,w});
        REP(i,4){
            int nh = h+vh[i];
            int nw = w+vw[i];
            if(!inside(nh,nw)) continue;
            if(C[nh][nw]=='#') continue;
            if(FIND(r[0],MP(nh,nw))) continue;
            q.push(MP(nh,nw));
        }
    }
    REP(i,H)REP(j,W){
        if(C[i][j]=='.'){
            //cout << i << " " << j << endl;
            if(FIND(r[0],MP(i,j))) continue;
            if(is[i][j]) continue;
            q.push({i,j});
            i = H; break;
        }
    }
    while(!q.empty()){
        auto p = q.front();
        q.pop();
        int h = p.first, w = p.second;
        if(is[h][w]) continue;
        is[h][w] = true;
        r[1].insert({h,w});
        REP(i,4){
            int nh = h+vh[i];
            int nw = w+vw[i];
            if(!inside(nh,nw)) continue;
            if(C[nh][nw]=='#') continue;
            if(FIND(r[1],MP(nh,nw))) continue;
            q.push(MP(nh,nw));
        }
    }
    int ans = INF;
    //REP(i,2) cout << r[i].size() << endl;
    FORE(el1,r[0])FORE(el2,r[1]){
        ans = min(ans,abs(el1.first-el2.first)+abs(el1.second-el2.second));
    }
    cout << ans-1 << endl;
}