#include <bits/stdc++.h>
#define rep(i,n) for (int i=0; i<(n); ++i)
using namespace std;
using ll = long long;
using P = pair<int,int>;

const int INF=1001001001;
int dy[4]={-1,0,1,0};
int dx[4]={0,-1,0,1};

int main(){
    int h,w;
    cin>>h>>w;
    int ans=0;
    vector<string>s(h);
    rep(i,h)cin>>s[i];
    rep(i,h)rep(j,w)if(s[i][j]=='.')ans++;
    vector<vector<int>>dist(h,vector<int>(w,INF));
    queue<P>q;
    q.push(P(0,0));
    dist[0][0]=1;
    while(!q.empty()){
        int y=q.front().first;
        int x=q.front().second;
        q.pop();
        rep(dir,4){
            int vy=y+dy[dir];
            int vx=x+dx[dir];
            if(vy<0||vy>=h||vx<0||vx>=w)continue;
            if(s[vy][vx]=='#'||dist[vy][vx]!=INF)continue;
            dist[vy][vx]=dist[y][x]+1;
            q.push(P(vy,vx));
        }
    }
    ans-=dist[h-1][w-1];
    if(dist[h-1][w-1]!=INF)cout<<ans<<endl;
    else cout<<-1<<endl;
}
#include<iostream>
#include<queue>
using namespace std;

int main() {
  int H, W; cin >> H >> W;
  int N = H*W;
  int A[N]; string str;
  int white_num = 0;
  for (int i = 0; i < H; i++) {
    cin >> str;
    for (int j = 0; j < W; j++) {
      white_num += A[i*W+j] = (str[j] == '.');
    }
  }
  queue<pair<int, int>> Q; Q.push(make_pair(0, 1));
  bool visited[N]; for (int i = 0; i < N; i++) visited[i] = false;
  visited[0] = true;
  int score = -1;
  while (!Q.empty()) {
    auto front = Q.front(); Q.pop();
    int u = front.first, d = front.second;
    if (u == H*W-1) { score = white_num-d; break; }
    vector<int> e;
    if (u >= W) e.push_back(u-W);
    if (u % W > 0) e.push_back(u-1);
    if (u % W < W-1) e.push_back(u+1);
    if (u / W < H-1) e.push_back(u+W);
    for (int v : e) {
      if (A[v] && !visited[v]) {
        visited[v] = true;
        Q.push(make_pair(v, d+1));
      }
    }
  }
  cout << score << endl;
}