#include<bits/stdc++.h>
using namespace std;
struct node{
	int x,y,step;
};
queue<node> q;
int n,m,sx,sy,zx,zy;
int fx[4]={0,1,0,-1};
int fy[4]={1,0,-1,0};
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 i=0;i<=3;i++)
		{
			int tx=x+fx[i];
			int ty=y+fy[i];
			if(tx>=1&&tx<=m&&ty>=1&&ty<=n&&a[tx][ty]!='#'){
				if(tx==zx&&ty==zy){
					cout<<step+1;
					return 0;
				}
				q.push({tx,ty,step+1});
				a[tx][ty]='#';
			}
		}
		q.pop();
	}
	cout<<-1;
}
/**************************************************************
	Problem: 1900
	User: wuyunfeng
	Language: C++
	Result: Accepted
	Time:9 ms
	Memory:2080 kb
****************************************************************/