#include <bits/stdc++.h>
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define rrep(i,n) for (int i = (n)-1; i >=0; --i)
template<class T> bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T> bool chmin(T &a, const T &b) { if (a>b) { a=b; return 1; } return 0; }

using namespace std;
using ll = long long;
using ld = long double;
using pi = pair<ll, ll>;

// auto mod int
// https://youtu.be/L8grWxBlIZ4?t=9858
// https://youtu.be/ERZuLAxZffQ?t=4807 : optimize
// https://youtu.be/8uowVvQ_-Mo?t=1329 : division
const int mod = 998244353;
struct mint {
  ll x; // typedef long long ll;
  mint(ll x=0):x((x%mod+mod)%mod){}
  mint operator-() const { return mint(-x);}
  mint& operator+=(const mint a) {
    if ((x += a.x) >= mod) x -= mod;
    return *this;
  }
  mint& operator-=(const mint a) {
    if ((x += mod-a.x) >= mod) x -= mod;
    return *this;
  }
  mint& operator*=(const mint a) { (x *= a.x) %= mod; return *this;}
  mint operator+(const mint a) const { return mint(*this) += a;}
  mint operator-(const mint a) const { return mint(*this) -= a;}
  mint operator*(const mint a) const { return mint(*this) *= a;}
  mint pow(ll t) const {
    if (!t) return 1;
    mint a = pow(t>>1);
    a *= a;
    if (t&1) a *= *this;
    return a;
  }

  // for prime mod
  mint inv() const { return pow(mod-2);}
  mint& operator/=(const mint a) { return *this *= a.inv();}
  mint operator/(const mint a) const { return mint(*this) /= a;}
};
istream& operator>>(istream& is, const mint& a) { return is >> a.x;}
ostream& operator<<(ostream& os, const mint& a) { return os << a.x;}
// combination mod prime
// https://www.youtube.com/watch?v=8uowVvQ_-Mo&feature=youtu.be&t=1619
struct combination {
  vector<mint> fact, ifact;
  combination(int n):fact(n+1),ifact(n+1) {
    assert(n < mod);
    fact[0] = 1;
    for (int i = 1; i <= n; ++i) fact[i] = fact[i-1]*i;
    ifact[n] = fact[n].inv();
    for (int i = n; i >= 1; --i) ifact[i-1] = ifact[i]*i;
  }
  mint operator()(int n, int k) {
    if (k < 0 || k > n) return 0;
    return fact[n]*ifact[k]*ifact[n-k];
  }
} c(200005);



int main() {
  ll r,cc, sy,sx,gy,gx;
  cin >> r>>cc;
  vector<vector<ll> > v(r, vector<ll>(cc));
  sx=0;sy=0;
  gx=cc-1;gy=r-1;
  string tmp;
  ll black = 0;

  rep(i, r) {
    cin >> tmp;
    rep(j, cc){
      if(tmp[j] == '.'){
	v[i][j] = 1e8;
      }
      else {
	v[i][j] = -1;
	black++;
      }
    }
  }
  queue<pi> q;
  q.push(make_pair(sy, sx));
  
  v[sy][sx] = 0;
  ll y = sy;
  ll x = sx;

  while(!q.empty()){
    pi hoge = q.front();
    q.pop();
    y = hoge.first;
    x = hoge.second;
    //cerr << y << " " << x<<endl;
    if(y-1>=0 && v[y-1][x]>1e7) {
      q.push(make_pair(y-1, x));
      v[y-1][x] =  v[y][x]+1;
    }
    if(x-1>=0 && v[y][x-1]>1e7){
      q.push(make_pair(y, x-1));
      v[y][x-1]= v[y][x]+1;
    }
    if(y+1<r&& v[y+1][x]>1e7){
      q.push(make_pair(y+1, x));
      v[y+1][x] = v[y][x]+1;
    }
    if(x+1<cc && v[y][x+1]>1e7){
      q.push(make_pair(y, x+1));
      v[y][x+1] = v[y][x]+1;
    }
  }
  ll ns = v[gy][gx];
  ll ans;
  
  if(ns>1e7) ans = -1;
  else ans = (r*cc-black - 1 - ns);
  
  
  cout << ans << endl;
  return 0;
}


Measured memory_bytes: 3456