#include <iostream>
#include <queue>
#include <cstring>
using namespace std;
const int N = 310;
char graph[N][N];
bool vis[N][N];
int n, m;
typedef pair<int, int> pii;
pii st, ed;
struct node{
    pii loc;
    int step;
};
int dic[4][2] = {
    {0, -1}, {-1, 0}, {0, 1}, {1, 0}  
};
bool check(int x, int y){
    if(x >= 0 && x < n && y >= 0 && y < m)  return true;
    return false;
}
int bfs(){
    queue<node> qu;
    qu.push({st, 0});
    vis[st.first][st.second] = true;
    while(!qu.empty()){
        node now = qu.front();
        qu.pop();
        for(int i = 0; i < 4; i ++ ){
            int xx = now.loc.first + dic[i][0];
            int yy = now.loc.second + dic[i][1];
            if(xx == ed.first && yy == ed.second)   return now.step + 1;
            if(check(xx, yy) && !vis[xx][yy] && graph[xx][yy] != '#'){
                vis[xx][yy] = true;
                qu.push({{xx, yy}, now.step + 1});
            }
        }
    }
    return -1;
}
int main(){
    while(cin >> n >> m && n && m){
        memset(vis, false, sizeof vis);
        for(int i = 0; i < n; i ++ ){
           for(int j = 0; j < m; j ++ ){
               cin >> graph[i][j];
               if(graph[i][j] == '@')   st = {i, j};
               if(graph[i][j] == '*')   ed = {i, j};
           } 
        }
        cout << bfs() << endl;
    }
    return 0;
}