#include<bits/stdc++.h>
using namespace std;
const int N=1e3+100;
int n,m,work[N],temp,ans;
char chr[5005][5005];
bool vis[5005][5005];
int dx[]={-1,0,0,1};
int dy[]={0,1,-1,0};
struct Edge
{
    int x,y,step;
};queue<Edge> q;
inline void inti()
{
    for(int i=0;pow(2,i)<=1000;i++)
    {
        work[++temp]=pow(2,i);
    }
    // for(int i=1;i<=temp;i++)
    // {
    //     cout<<work[i]<<" ";
    // }
    // cout<<endl;
    return ;
}
inline bool check(int x,int y)
{
    if(x>=1 and x<=n and y>=1 and y<=m and vis[x][y]==false)
    {
        return true;
    }
    return false;
}
inline void BFS(int x,int y)
{
    q.push(Edge{x,y,0});vis[x][y]=true;
    //cout<<q.size()<<endl;
    while(!q.empty())
    {
        Edge head=q.front();q.pop();
        if(chr[head.x][head.y]=='#')
        {
            ans=head.step;
            return ;
        }
        for(int i=0;i<4;i++)
        {
            for(int j=1;j<=temp;j++)
            {
                int xx=dx[i]*work[j]+head.x,yy=dy[i]*work[j]+head.y;
                if(check(xx,yy)==true)
                {
                    if(chr[xx][yy]=='X' or chr[xx][yy]=='.')
                    {
                        break;
                    }
                    q.push(Edge{xx,yy,head.step+1});vis[xx][yy]=true;
                }
            }
        }
    }
    ans=-1;
    return ;
}
signed main(void)
{
    inti();
    scanf("%d%d",&n,&m);
    for(int i=1;i<=n;i++)
    {
        for(int j=1;j<=m;j++)
        {
            cin>>chr[i][j];
        }
    }
    BFS(1,1);
    printf("%d\n",ans);
    return 0;
}