/*input
4 4
1 1
4 4
..#.
..#.
.#..
.#..
*/
 
/*
                                                    ______________
                                                          |       )
                                                          |   )   /
                                                          |______/
                                                    |     |      \
                                                    |     |   )   \
                                                    |_____|_______)
 
*/
#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <algorithm>
#include <cmath>
#include <vector>
#include <set>
#include <map>
#include <unordered_set>
#include <unordered_map>
#include <queue>
#include <ctime>
#include <cassert>
#include <complex>
#include <string>
#include <cstring>
#include <chrono>
#include <random>
#include <queue>
#include <bitset>
#include <iomanip>
#include <fstream>
#include <stack>

using namespace std;
 
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int,int> PII;
typedef pair<ll , ll> PLL;
typedef long double ld;
 
#define pb push_back
#define all(c) c.begin(),c.end()
#define allr(c) c.rbegin(),c.rend()
int mod = 1000000007;
const int inf = 1034567891;
const ll LL_INF = 1234567890123456789ll;
#define PI 3.14159265
#define endl '\n'
#define F first
#define S second
#define debug(x) cout << #x << " = " << x << endl;
#define TRACE
 
#ifdef TRACE
#define trace(...) __f(#__VA_ARGS__, __VA_ARGS__)
template <typename Arg1>
void __f(const char* name, Arg1&& arg1){
  cout << name << " : " << arg1 << endl;
}
template <typename Arg1, typename... Args>
void __f(const char* names, Arg1&& arg1, Args&&... args){
  const char* comma = strchr(names + 1, ',');cout.write(names, comma - names) << " : " << arg1<<" | ";__f(comma+1, args...);
}
#else
#define trace(...)
#endif
 
#define out(container) for (auto it : container) cout << it << " "; cout << endl;
 
 
template < typename T > T GCD(T a, T b)            { ll t; while(a) { t = a; a = b % a; b = t; } return b; }
template < typename T > string toString(T a)       { return to_string(a); }
template < typename T > void toInt(string s, T &x) { stringstream str(s); str >> x;}
inline int add(int x, int y){ x += y; if(x >= mod) x -= mod; return x;}
inline int sub(int x, int y){ x -= y; if(x < 0) x += mod; return x;}
inline int mul(int x, int y){ return (x * 1ll * y) % mod;}
inline int powr(int a, ll b){
  int x = 1 % mod;
  while(b){
    if(b & 1) x = mul(x, a);
    a = mul(a, a);
    b >>= 1;
  }
  return x;
}
inline int inv(int a){ return powr(a, mod - 2);}

const int N = 1e6 + 5;

vector<PII> adj[N];

int cost[N];

int main()
{
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  
  int n, m;
  cin >> n >> m;
  int ch, dh, cw, dw;
  cin >> ch >> dh >> cw >> dw;

  char arr[n + 1][m + 1];

  int nodeVal[n + 1][m + 1];

  int x = 1;

  for (int i = 1; i <= n; i++) {
    for (int j = 1; j <= m; j++) {
      cin >> arr[i][j];
      cost[x] = inf;
      nodeVal[i][j] = x++;
    }
  }

  for (int i = 1; i <= n; i++) {
    for (int j = 1; j <= m; j++) {
      if (arr[i][j] == '#') continue;
      for (int x = -2; x <= 2; x++) {
        for (int y = -2; y <= 2; y++) {
          if (x == 0 && y == 0) continue;
          if (i + x < 1 || i + x > n) continue;
          if (j + y < 1 || j + y > m) continue;
          if (arr[i + x][j + y] != '.') continue;
          int d = abs(x) + abs(y);
          int c = (d > 1);
          int u = nodeVal[i][j], v = nodeVal[i + x][j + y];
          adj[u].push_back({v, c});
        }
      }
    }
  }

  int s = nodeVal[ch][dh], d = nodeVal[cw][dw];

  vector<bool> vis(x + 5, false);
  priority_queue<PII, vector<PII>, greater<PII>> pq;

  pq.push({0, s});

  int ans = inf;

  while (!pq.empty()) {
    PII p = pq.top();
    pq.pop();
    s = p.S;
    int w = p.F;
    vis[s] = true;

    if (s == d) {
      ans = w;
      break;
    }

    for (auto it : adj[s]) {
      if (!vis[it.F] && w + it.S < cost[it.F]) {
        cost[it.F] = w + it.S;
        pq.push({cost[it.F], it.F});
      }
    }
  }

  if (ans == inf)
    ans = -1;

  cout << ans << endl;

  return 0;
}

Measured memory_bytes: 105776