#include<bits/stdc++.h>

#define fastio ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define ll long long
#define pii pair<int,int>
#define pill pair<int,ll>
#define pll pair<ll,ll>
#define pb push_back
#define fi first
#define se second
#define ff fi.fi
#define fs fi.se
#define sf se.fi
#define ss se.se
#define MASK(x) (((1)<<(x))-1)
#define getbit(x,k) (((x)>>(k))&1)

using namespace std;

const int maxn=1e3+5,mod=1e9+7;
const ll inf=1e18;

int n,m;
int dx[]={0,0,-1,1,-1,-1,1,1},dy[]={1,-1,0,0,-1,1,-1,1};
int ans;
void bfs(vector<vector<char>>A, vector<vector<int>>d)
{
    deque<pair<int,pii>>dQ;
    for(int i=1;i<=n;i++) if(A[i][1]!='@')
    {
        d[i][1]=(A[i][1]=='.');
        if(d[i][1]) dQ.push_back({1,{i,1}});
        else dQ.push_front({0,{i,1}});
    }
    for(int i=1;i<=m;i++) if(A[n][i]!='@')
    {
        d[n][i]=(A[n][i]=='.');
        if(d[n][i]) dQ.push_back({1,{n,i}});
        else dQ.push_front({0,{n,i}});
    }
    while(dQ.size())
    {
        pair<int,pii> u=dQ.front();dQ.pop_front();
        if(u.fi!=d[u.sf][u.ss]) continue;
        int x=u.sf,y=u.ss;
        if(x==1 || y==m) ans=min(ans,u.fi);
        for(int k=0;k<8;k++)
        {
            int nx=x+dx[k],ny=y+dy[k],c=1;
            if(nx<1 || nx>n || ny<1 || ny>m) continue;
            if(A[nx][ny]=='@') continue;
            if(A[nx][ny]=='#') c=0;
            if(d[nx][ny]>u.fi+c)
            {
                d[nx][ny]=u.fi+c;
                if(c==0) dQ.push_front({u.fi,{nx,ny}});
                else dQ.push_back({d[nx][ny],{nx,ny}});
            }
        }
    }
}
int main()
{
    fastio
    while(cin>>n>>m)
    {
        if(!n && !m) break;
        vector<vector<char>>A;
        vector<vector<int>>d;
        A.assign(n+10,vector<char>(m+10,'0'));
        d.assign(n+10,vector<int>(m+10,1e9));
        for(int i=1;i<=n;i++)
            for(int j=1;j<=m;j++)
                cin>>A[i][j];
        ans=1e9;
        bfs(A,d);
        if(ans==1e9) ans=-1;
        cout<<ans<<'\n';
    }
}