#pragma region template
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ull = unsigned long long;
using ld = long double;
using vi = vector<int>;
using vvi = vector<vi>;
using vvvi = vector<vvi>;
using vll = vector<ll>;
using vvll = vector<vll>;
using vvvll = vector<vvll>;
using vld = vector<ld>;
using vvld = vector<vld>;
using vvvld = vector<vvld>;
using vs = vector<string>;
using pll = pair<ll, ll>;
using vp = vector<pll>;
template <typename T>
using pqrev = priority_queue<T, vector<T>, greater<T>>;
#define rep(i, n) for (ll i = 0, i##_end = (n); i < i##_end; i++)
#define repb(i, n) for (ll i = (n)-1; i >= 0; i--)
#define repr(i, a, b) for (ll i = (a), i##_end = (b); i < i##_end; i++)
#define reprb(i, a, b) for (ll i = (b)-1, i##_end = (a); i >= i##_end; i--)
#define ALL(a) (a).begin(), (a).end()
#define SZ(x) ((ll)(x).size())
//*
constexpr ll MOD = 1e9 + 7;
/*/
constexpr ll MOD = 998244353;
//*/
constexpr ll INF = 1e+18;
constexpr ld EPS = 1e-12L;
constexpr ld PI = 3.14159265358979323846L;
constexpr ll GCD(ll a, ll b) { return b ? GCD(b, a % b) : a; }
constexpr ll LCM(ll a, ll b) { return a / GCD(a, b) * b; }
template <typename S, typename T>
inline bool chmax(S &a, const T &b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
template <typename S, typename T>
inline bool chmin(S &a, const T &b) {
  if (b < a) {
    a = b;
    return 1;
  }
  return 0;
}
#ifdef OJ_LOCAL
#include "dump.hpp"
#else
#define dump(...) ((void)0)
#endif
template <typename T>
bool print_(const T &a) {
  cout << a;
  return true;
}
template <typename T>
bool print_(const vector<T> &vec) {
  for (auto &a : vec) {
    cout << a;
    if (&a != &vec.back()) {
      cout << " ";
    }
  }
  return false;
}
template <typename T>
bool print_(const vector<vector<T>> &vv) {
  for (auto &v : vv) {
    for (auto &a : v) {
      cout << a;
      if (&a != &v.back()) {
        cout << " ";
      }
    }
    if (&v != &vv.back()) {
      cout << "\n";
    }
  }
  return false;
}
void print() { cout << "\n"; }
template <typename Head, typename... Tail>
void print(Head &&head, Tail &&... tail) {
  bool f = print_(head);
  if (sizeof...(tail) != 0) {
    cout << (f ? " " : "\n");
  }
  print(forward<Tail>(tail)...);
}
#pragma endregion

int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  cout << fixed << setprecision(20);
  ll h, w;
  cin >> h >> w;
  ll ch, cw;
  cin >> ch >> cw;
  ll dh, dw;
  cin >> dh >> dw;
  vs s(h);
  rep(i, h){
    cin >> s[i];
  }
  vvll dist(h, vll(w, INF));
  auto bfs = [&](int si, int sj) -> void{
    deque<tuple<int, int>> q;
    q.emplace_back(si, sj);
    dist[si][sj] = 0;
    while(q.size()){
      auto fr = q.front();
      /*
      if(get<0>(fr) == dh-1 && get<1>(fr) == dw-1){
        print(get<2>(fr));
        return;
      }
      */
      q.pop_front();
      repr(di, -2, 3)repr(dj, -2, 3){
        if(di == 0 && dj == 0) continue;
        int ni = get<0>(fr) + di;
        int nj = get<1>(fr) + dj;
        int c = abs(di)+abs(dj) > 1;
        int d = dist[get<0>(fr)][get<1>(fr)] + c;
        if(ni < 0 || ni >= h
        || nj < 0 || nj >= w)
          continue;
        if(s[ni][nj] == '.' && d < dist[ni][nj]){
          dist[ni][nj] = d;
          if(c) q.emplace_back(ni, nj);
          else q.emplace_front(ni, nj);
        }
      }
    }
  };
  bfs(ch-1, cw-1);
  print(dist[dh-1][dw-1] == INF ? -1 : dist[dh-1][dw-1]);
}


Measured memory_bytes: 12628