#include <bits/stdc++.h>
using namespace std;
string s[20];
int n, m, dx[] = {1, 0, -1, 0}, dy[] = {0, 1, 0, -1};
map<vector<int>, int> mp;
queue<vector<int>> q;
int vis[20][20];
void dfs(int x, int y) {
  if (x < 1 || x > n || y < 1 || y > m || s[x][y] == '#' || vis[x][y]) return;
  vis[x][y] = 1;
  for (int i = 0; i < 4; i++) {
    dfs(x + dx[i], y + dy[i]);
  }
}
int main() {
  cin >> n >> m;
  for (int i = 1; i <= n; i++) {
    cin >> s[i];
    s[i] = " " + s[i];
  }
  vector<int> init;
  for (int k = 1; k <= 9; k++) {
    for (int i = 1; i <= n; i++) {
      for (int j = 1; j <= m; j++) {
        if (s[i][j] == '0' + k) {
          init.push_back(i);
          init.push_back(j);
        }
      }
    }
  }
  dfs(init[0], init[1]);
  bool ans = 0;
  for (int i = 1; i <= n; i++) {
    for (int j = 1; j <= m; j++)
      if (s[i][j] == '@' && vis[i][j]) ans = true;
  }
  if (!ans) {
    cout << -1 << endl;
    return 0;
  }
  int k = init.size() / 2;
  mp[init] = 0;
  q.push(init);
  while (!q.empty()) {
    vector<int> v = q.front();
    q.pop();
    int d = mp[v];
    for (int i = 0; i < 4; i++) {
      int x = v[0] + dx[i];
      int y = v[1] + dy[i];
      if (x < 1 || x > n || y < 1 || y > m || s[x][y] == '#') continue;
      bool ans = false;
      for (int j = 0; j < k - 1; j++) {
        if (x == v[2 * j] && v[2 * j + 1] == y) ans = true;
      }
      if (ans) continue;
      if (s[x][y] == '@') {
        cout << d + 1 << endl;
        return 0;
      }
      vector<int> w(2 * k);
      w[0] = x;
      w[1] = y;
      for (int j = 0; j < 2 * k - 2; j++) w[j + 2] = v[j];
      if (mp.find(w) == mp.end()) {
        mp[w] = d + 1;
        q.push(w);
      }
    }
  }
  cout << -1 << endl;
  return 0;
}
