Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209
#include <bits/stdc++.h>
#define ll long long
using namespace std;
typedef pair<int,int> P;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)


int h,w;
char maze[60][60];
int x,y;
int d[60][60];
int dx[4]={-1,0,1,0}; int dy[4]={0,1,0,-1};


int main(){
  cin >>h>>w;
  int black=0;
  rep(i,h){
    rep(j,w){
      cin >> maze[i][j];
      if(maze[i][j]=='#'){
        black++;
      }
    }
  }
  queue<P>que;
  rep(i,h){rep(j,w){d[i][j]=100000;}}
  d[0][0]=0;
  que.push(P(0,0));

  while(que.size()){
    P p=que.front(); que.pop();
    for (int i=0; i<4; i++){
      int ny=p.first+dy[i] ; int nx = p.second+dx[i];
      if(nx>=0 && nx<w && ny>=0 && ny<h && d[ny][nx]==100000 &&maze[ny][nx]!='#'){
          d[ny][nx]=d[p.first][p.second] +1;
          que.push(P(ny,nx));
      }
      }
    }
  

  if(d[h-1][w-1]!=100000){
    cout << h*w-black-d[h-1][w-1]-1<<endl;
  }
  else{
    cout<<-1<<endl;
  }
  


}
