#include <iostream>
#include <cstring>
#include <queue>

using namespace std;

const int N = 310;

typedef pair<int, int> PII;

int n, m;
char g[N][N];
int dist[N][N];

int bfs(int a, int b)
{
    memset(dist, -1, sizeof dist);
    dist[a][b] = 0;

    queue<PII> q;
    q.push({a, b});

    int dx[4] = {0, 0, -1, 1}, dy[4] = {1, -1, 0, 0};
    while (q.size())
    {
        auto t = q.front();
        q.pop();

        for (int i = 0; i < 4; i ++ )
        {
            int x = t.first + dx[i], y = t.second + dy[i];
            if (x >= 0 && x < m && y >= 0 && y < n && g[x][y] != '#' && dist[x][y] == -1)
            {
                dist[x][y] = dist[t.first][t.second] + 1;
                q.push({x, y});
            }
        }
    }

    for (int i = 0; i < m; i ++ )
        for (int j = 0; j < n ; j ++ )
            if (g[i][j] == '*')
                return dist[i][j];
}

int main()
{
    while (true)
    {
        cin >> m >> n;
        if (m == 0 && n == 0) break;

        int x, y;
        for (int i = 0; i < m; i ++ )
            for (int j = 0; j < n; j ++ )
            {
                cin >> g[i][j];
                if (g[i][j] == '@')
                {
                    x = i, y = j;
                }
            }

        cout << bfs(x, y) << endl;
    }

    return 0;
}