#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: zhouhongyi
	Language: C++
	Result: Accepted
	Time:11 ms
	Memory:2080 kb
****************************************************************/