#include<bits/stdc++.h>
using namespace std;
struct noi{
	int x;
	int y;
	int t;
}; 
queue<noi> yu;
int dx[4]={1,0,-1,0};
int dy[4]={0,1,0,-1};
int m,n,sx,sy,ex,ey;
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]=='*'){
				ex=i;
				ey=j;
			}
		}
	}
	yu.push({sx,sy,0});
	a[sx][sy]='#';
	while(!yu.empty()){
		int x=yu.front().x;
		int y=yu.front().y;
		int t=yu.front().t;
		for(int i=0;i<=3;i++){
			int tx=x+dx[i];
			int ty=y+dy[i];
			if(tx>=1&&tx<=m&&ty>=1&&ty<=n&&a[tx][ty]!='#'){
				if(tx==ex&&ty==ey){
					cout<<t+1;
					return 0;
				}
				yu.push({tx,ty,t+1});
				a[tx][ty]='#';
			}
		}
		yu.pop();
	}
	cout<<-1;
	return 0;
}
/*
5 9
3 1 4 1 5
0

6 1
1 6 1 2 0 4
11
84
73264529

10 5 8 10 9 7 11
4  1        
6  4 0  6 4 1  5
*/
/**************************************************************
	Problem: 1900
	User: huangsheng
	Language: C++
	Result: Accepted
	Time:9 ms
	Memory:2080 kb
****************************************************************/