#include <bits/stdc++.h>
using namespace std;
//#include <boost/multiprecision/cpp_int.hpp>
//using multiInt = boost::multiprecision::cpp_int;

using ll = long long int;
using ld = long double;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
template <typename Q_type>
using smaller_queue = priority_queue<Q_type, vector<Q_type>, greater<Q_type>>;

const int MOD_TYPE = 1;
const ll MOD = (MOD_TYPE == 1 ? (ll)(1e9 + 7) : 998244353);
const int INF = (int)1e9;
const ll LINF = (ll)4e18;
const ld PI = acos(-1.0);
const ld EPS = 1e-11;

#define REP(i, m, n) for (ll i = m; i < (ll)(n); ++i)
#define rep(i, n) REP(i, 0, n)
#define MP make_pair
#define MT make_tuple
#define YES(n) cout << ((n) ? "YES" : "NO") << endl
#define Yes(n) cout << ((n) ? "Yes" : "No") << endl
#define Possible(n) cout << ((n) ? "Possible" : "Impossible") << endl
#define possible(n) cout << ((n) ? "possible" : "impossible") << endl
#define Yay(n) cout << ((n) ? "Yay!" : ":(") << endl
#define all(v) v.begin(), v.end()
#define NP(v) next_permutation(all(v))
#define dbg(x) cerr << #x << ":" << x << endl;

vector<int> Dx = {0, 0, -1, 1, -1, 1, -1, 1, 0};
vector<int> Dy = {1, -1, 0, 0, -1, -1, 1, 1, 0};

template <typename T = ll>
struct dijkstra
{
  static const int MAX_V = 1000010;
  const T INF_d;
  dijkstra(T INF_d_ = LINF) : INF_d(INF_d_) {}

  struct edge
  {
    int to;
    T cost;
  };

  vector<edge> E[MAX_V];
  T d[MAX_V];
  using pt = pair<T, int>;

  void add_E(int a, int b, T c, bool undirected = false)
  {
    E[a].push_back(edge{b, c});
    if (undirected)
      E[b].push_back(edge{a, c});
  }

  void calc(int s)
  {
    priority_queue<pt, vector<pt>, greater<pt>> que;
    fill(d, d + MAX_V, INF_d);
    que.emplace(0LL, s);
    d[s] = 0;
    while (!que.empty())
    {
      pt p = que.top();
      que.pop();
      int v = p.second;
      if (d[v] < p.first)
        continue;
      for (auto &&e : E[v])
      {
        if (d[e.to] > d[v] + e.cost)
        {
          d[e.to] = d[v] + e.cost;
          que.emplace(d[e.to], e.to);
        }
      }
    }
  }
};

int main()
{
  cin.tie(0);
  ios::sync_with_stdio(false);
  cout << setprecision(30) << setiosflags(ios::fixed);

  int r, c;
  cin >> r >> c;
  int sr, sc, gr, gc;
  cin >> sr >> sc >> gr >> gc;
  char s[1010][1010];
  rep(i, r + 2) rep(j, c + 2)
  {
    if (i == 0 || i == r + 1 || j == 0 || j == c + 1)
      s[i][j] = '.';
    else
      cin >> s[i][j];
  }
  r += 2, c += 2;
  dijkstra<ll> ds;
  rep(i, r) rep(j, c)
  {
    if (s[i][j] == '#')
      continue;
    if (i + 1 < r && s[i + 1][j])
      ds.add_E(i * c + j, (i + 1) * c + j, 1, true);
    if (j + 1 < c && s[i][j + 1])
      ds.add_E(i * c + j, i * c + j + 1, 1, true);
  }
  ds.calc(sr * c + sc);
  cout << ds.d[gr * c + gc] << endl;
  return 0;
}