#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
using namespace std;
#define FOR(i,m,n) for(int i=(m);i<(n);++i)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) (v).begin(),(v).end()
using ll = long long;
constexpr int INF = 0x3f3f3f3f;
constexpr long long LINF = 0x3f3f3f3f3f3f3f3fLL;
constexpr double EPS = 1e-8;
constexpr int MOD = 1000000007;
// constexpr int MOD = 998244353;
constexpr int dy[] = {1, 0, -1, 0}, dx[] = {0, -1, 0, 1};
constexpr int dy8[] = {1, 1, 0, -1, -1, -1, 0, 1}, dx8[] = {0, -1, -1, -1, 0, 1, 1, 1};
template <typename T, typename U> inline bool chmax(T &a, U b) { return a < b ? (a = b, true) : false; }
template <typename T, typename U> inline bool chmin(T &a, U b) { return a > b ? (a = b, true) : false; }
struct IOSetup {
  IOSetup() {
    std::cin.tie(nullptr);
    std::ios_base::sync_with_stdio(false);
    std::cout << fixed << setprecision(20);
  }
} iosetup;

int main() {
  int h, w, ra, ca, rb, cb; cin >> h >> w >> ra >> ca >> rb >> cb; --ra; --ca; --rb; --cb;
  vector<string> s(h); REP(i, h) cin >> s[i];
  vector dist(h, vector(w, -1));
  dist[ra][ca] = 0;
  vector prev(h, vector(w, make_pair(-1, -1)));
  queue<pair<int, int>> que({{ra, ca}});
  while (!que.empty()) {
    auto [i, j] = que.front(); que.pop();
    REP(k, 4) {
      int y = i + dy[k], x = j + dx[k];
      if (dist[y][x] == -1 && s[y][x] == '.') {
        dist[y][x] = dist[i][j] + 1;
        prev[y][x] = {i, j};
        que.emplace(y, x);
      }
    }
  }
  if (dist[rb][cb] == -1) {
    cout << "-1\n";
    return 0;
  }
  int ans = INF;
  {
    int cnt = 0;
    REP(k, 4) {
      int y = ra + dy[k], x = ca + dx[k];
      cnt += s[y][x] == '.';
    }
    if (cnt >= 3) chmin(ans, dist[rb][cb] * 2 + 4);
  }
  {
    int cnt = 0;
    REP(k, 4) {
      int y = rb + dy[k], x = cb + dx[k];
      cnt += s[y][x] == '.';
    }
    if (cnt >= 3) chmin(ans, dist[rb][cb] * 2 + 4);
  }
  s[rb][cb] = 'b';
  int cr = rb, cc = cb;
  while (cr != ra || cc != ca) {
    tie(cr, cc) = prev[cr][cc];
    s[cr][cc] = '$';
  }
  s[ra][ca] = 'a';
  REP(i, h) REP(j, w) {
    if (s[i][j] == '$') {
      REP(k, 4) {
        int y = i + dy[k], x = j + dx[k];
        if (s[y][x] == '.') chmin(ans, dist[rb][cb] * 2 + 2);
      }
    }
  }
  s[ra][ca] = s[rb][cb] = '$';
  // REP(i, h) cout << s[i] << '\n';
  vector bfs1(h, vector(w, -1));
  vector bfs2(h, vector(w, vector<int>{}));
  vector<tuple<int, int, vector<int>>> que2;
  REP(i, h) REP(j, w) {
    if (s[i][j] == '$') {
      bfs1[i][j] = 0;
      bfs2[i][j] = {dist[i][j]};
      que2.emplace_back(i, j, vector<int>{dist[i][j]});
    }
  }
  while (!que2.empty()) {
    map<pair<int, int>, vector<int>> nx_mp;
    for (auto [i, j, ds] : que2) {
      int nx_dist = bfs1[i][j] + 1;
      REP(k, 4) {
        int y = i + dy[k], x = j + dx[k];
        if (s[y][x] == '.') {
          if (bfs1[y][x] == -1) {
            bfs1[y][x] = nx_dist;
            bfs2[y][x] = ds;
            nx_mp[{y, x}] = ds;
          } else if (bfs1[y][x] == nx_dist) {
            for (int a : ds) for (int b : bfs2[y][x]) {
              if (a != b) {
                int tmp = bfs1[y][x] + nx_dist - abs(a - b);
                assert(tmp >= 0);
                chmin(ans, dist[rb][cb] * 2 + tmp);
                nx_mp[{y, x}].emplace_back(a);
              }
            }
          } else {
            for (int a : ds) for (int b : bfs2[y][x]) {
              if (a != b) {
                int tmp = bfs1[y][x] + nx_dist - abs(a - b);
                assert(tmp >= 0);
                chmin(ans, dist[rb][cb] * 2 + tmp);
              }
            }
          }
        }
      }
    }
    que2.clear();
    for (auto [ij, ds] : nx_mp) que2.emplace_back(ij.first, ij.second, ds);
  }
  cout << (ans == INF ? -1 : ans) << '\n';
  return 0;
}