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>
using namespace std;

long long h,w,x,y,X,Y,cnt=0;
int dx[]={0,1,0,-1};
int dy[]={1,0,-1,0};
string s[100];
bool B[100][100];

int bfs(){
  queue<tuple<int,int,int>> q;
  q.push(tuple<int,int,int>(0,0,0));
  tuple<int,int,int> p;
  int d;
  while(q.size()){
    tie(y,x,d)=q.front();q.pop();
    if(x==w-1&&y==h-1){
      return d;
    }
    for(int i=0;i<4;i++){
      X=x+dx[i];
      Y=y+dy[i];
      if(X>=0&&X<w&&Y>=0&&Y<h&&s[Y][X]!='#'&&B[Y][X]==0){
        q.push(tuple<int,int,int>(Y,X,d+1));
        B[Y][X]=1;
      }
    }
  }
  return 0;
}

int main(){
  cin >> h >> w;  
  for(int i=0;i<h;i++){
    cin >> s[i];
    for(int j=0;j<s[i].size();j++){
      if(s[i][j]=='.'){
        cnt++;
      }
    }
  }  
  long long tmp=bfs();
  if(B[h-1][w-1]){
    cout << cnt-tmp-1 << endl;
  }else{
    cout << -1 << endl;
  }
  return 0;
}
