#include<bits/stdc++.h>
using namespace std;
int n,m,sum_p=0;
struct node{
int x,y;
};
char road[55][55];
int book[55][55];
int dir[][2]={{1,0},{-1,0},{0,-1},{0,1}};
void bfs(int sx,int sy){
queue<node> q;
q.push({sx,sy});
book[sx][sy]=1;
while(q.size()){
int tx=q.front().x,ty=q.front().y;
q.pop();
for(int i=0;i<4;++i){
int nx=tx+dir[i][0],ny=ty+dir[i][1];
if(nx<1||nx>n||ny<1||ny>m||road[nx][ny]'#')continue;
else if(road[nx][ny]'.'&&!book[nx][ny]){
q.push({nx,ny});
book[nx][ny]=book[tx][ty]+1;
}
}
}
// cout<<book[n][m];
}
int main(){
ios::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
cin>>n>>m;
for(int i=1;i<=n;++i)
for(int j=1;j<=m;j){
cin>>road[i][j];
if(road[i][j]=='.')sum_p;
}
bfs(1,1);
n==2?cout<<2:(book[n][m]?cout<<sum_p-book[n][m]:cout<<-1);
cout<<"\n";
return 0;
}
