#include <bits/stdc++.h>
using namespace std;
struct Note{
    int x,y,step;
};
queue<Note> q;
int m,n,fx[4]={0,0,-1,1},fy[4]={1,-1,0,0},sx,sy,zx,zy;
char a[50][50];
int main(){
    cin>>m>>n;
    for(int i=1;i<=m;i++){
        for(int j=1;j<=n;j++){
            cin>>a[i][j];
            if(a[i][j]=='@')sx=i,sy=j;
            if(a[i][j]=='*')zx=i,zy=j;
        }
    }
    q.push({sx,sy,0});
    a[sx][sy]='#';
    while(!q.empty()){
        int x=q.front().x;
        int y=q.front().y;
        int step=q.front().step;
        for(int j=0;j<=3;j++){
            int tx=x+fx[j];
            int ty=y+fy[j];
            if(a[tx][ty]!='#'&&tx>0&&ty>0&&tx<=m&&ty<=n){
                if(a[tx][ty]=='*'){
                    cout<<step+1;
                    return 0;
                }
                q.push({tx,ty,step+1});
            }
            a[tx][ty]='#';
        }
        q.pop();
    }
    cout<<-1;
    return 0;
}
/**************************************************************
	Problem: 1900
	User: caijiajie
	Language: C++
	Result: Accepted
	Time:10 ms
	Memory:2080 kb
****************************************************************/