#include<bits/stdc++.h>
#include<atcoder/all>
using namespace std;
using namespace atcoder;
typedef long long int ll;
typedef long double ld;
typedef vector<ll> vi;
typedef vector<vi> vvi;
typedef vector<vvi> vvvi;
typedef vector<vvvi> vvvvi;
typedef pair<ll,ll> pi;
typedef pair<ll,pi> ppi;
typedef pair<ll,ppi> pppi;
typedef pair<ll,pppi> ppppi;
#define FOR(i,l,r) for(ll i=l;i<r;i++)
#define REP(i,n) FOR(i,0,n)
#define RFOR(i,l,r) for(ll i=r-1;i>=l;i--)
#define RREP(i,n) RFOR(i,0,n)
#define ALL(x) x.begin(),x.end()
#define F first
#define S second
#define BS(A,x) binary_search(ALL(A),x)
#define LB(A,x) (ll)(lower_bound(ALL(A),x)-A.begin())
#define UB(A,x) (ll)(upper_bound(ALL(A),x)-A.begin())
#define COU(A,x) (UB(A,x)-LB(A,x))
#define sz(c) ((ll)(c).size())
/*
#include<boost/multiprecision/cpp_int.hpp>
namespace mp=boost::multiprecision;
using Bint=mp::cpp_int;
*/
template<typename T>using min_priority_queue=priority_queue<T,vector<T>,greater<T>>;
template<typename T1,typename T2>ostream&operator<<(ostream&os,pair<T1,T2>&p){os<<p.F<<" "<<p.S;return os;}
template<typename T1,typename T2>istream&operator>>(istream&is,pair<T1,T2>&p){is>>p.F>>p.S;return is;}
template<typename T>ostream&operator<<(ostream&os,vector<T>&v){REP(i,sz(v))os<<v[i]<<(i+1!=sz(v)?" ":"");return os;}
template<typename T>istream&operator>>(istream&is,vector<T>&v){for(T&in:v)is>>in;return is;}
template<class T>bool chmax(T&a,T b){if(a<b){a=b;return 1;}return 0;}
template<class T>bool chmin(T&a,T b){if(b<a){a=b;return 1;}return 0;}
ld dist(ld x1,ld y1,ld x2,ld y2){return sqrtl((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));}
//*
using mint=modint998244353;
const ll mod=998244353;
const ld EPS=1e-8;
//*/
/*
using mint=modint1000000007;
const ll mod=1000000007;
//*/
//using mint=modint;
//*
typedef vector<mint> vm;
typedef vector<vm> vvm;
typedef vector<vvm> vvvm;
typedef vector<vvvm> vvvvm;
ostream&operator<<(ostream&os,mint&a){os<<a.val();return os;}
//*/
bool able(vector<string>S){
	ll H=sz(S),W=sz(S[0]);
	vector<vector<bool>>ABLE(H-1,vector<bool>(W-1,1)),DP(H-2,vector<bool>(W-2));
	REP(i,H-2)REP(j,W-2){
		REP(x,3)REP(y,3)if(S[i+x][j+y]=='#')ABLE[i][j]=0;
	}
	
	REP(i,H-1)ABLE[i][W-2]=0;
	REP(i,W-1)ABLE[H-2][i]=0;
	DP[0][0]=1;
	queue<pi>Q;Q.emplace(pi(0,0));
	while(sz(Q)){
		ll x=Q.front().F,y=Q.front().S;
		Q.pop();
		FOR(dx,-1,2)FOR(dy,-1,2)if(x+dx>=0&&y+dy>=0&&ABLE[x+dx][y+dy]&&!DP[x+dx][y+dy]){
			Q.emplace(pi(x+dx,y+dy));
			DP[x+dx][y+dy]=1;
		}
	}
	return DP[H-3][W-3];
}
int main(){
  ll H,W;cin>>H>>W;
  ll ans=2;
  vector<string>S(H);cin>>S;
  if(!able(S)){cout<<0<<endl;return 0;}
  REP(i,H)REP(j,W)if(S[i][j]=='.'){
  	if((i>2||j>2)&&(i<H-3||j<W-3)){
  		S[i][j]='#';
  		if(!able(S))ans=1;
  		S[i][j]='.';
  	}
  }
  cout<<ans<<endl;
  return 0;
}