#include <bits/stdc++.h>
#include <vector>
#include <set>
#include <map>
#include <string>
#include <cstdio>
#include <cstdlib>
#include <climits>
#include <utility>
#include <algorithm>
#include <cmath>
#include <queue>
#include <stack>
#include <iomanip>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp> 
//setbase - cout << setbase (16); cout << 100 << endl; Prints 64
//setfill -   cout << setfill ('x') << setw (5); cout << 77 << endl; prints xxx77
//setprecision - cout << setprecision (14) << f << endl; Prints x.xxxx
//cout.precision(x)  cout<<fixed<<val;  // prints x digits after decimal in val
 
using namespace std;
using namespace __gnu_pbds;
 	// find_by_order()  // order_of_key
typedef tree<
int,
null_type,
less<int>,
rb_tree_tag,
tree_order_statistics_node_update>
ordered_set;
#define f(i,a,b) for(ll i=a;i<b;i++)
#define fi(i,a,b) for(int i=a;i<b;i++)
#define rep(i,n) f(i,0,n)
#define fd(i,a,b) for(ll i=a;i>=b;i--)
#define pb push_back
#define mp make_pair
#define vi vector< int >
#define vl vector< ll >
#define ss second
#define ff first
#define ll long long
#define pii pair< int,int >
#define pll pair< ll,ll >
#define sz(a) a.size()
#define inff (1000*1000*1000+5)
#define all(a) a.begin(),a.end()
#define tri pair<int,pii>
#define vii vector<pii>
#define vll vector<pll>
#define viii vector<tri>
#define pqueue priority_queue< int >
#define pdqueue priority_queue< int,vi ,greater< int > >
#define flush fflush(stdout) 
#define primeDEN 727999983
#define SPEED ios_base::sync_with_stdio(false) ;cin.tie(NULL) ;cout.tie(NULL) ;
#define fp(i,a,n) for(ll i=n-1; i>a ;i--)
#define deb(x) cout << #x << " ---> " << x << endl;
#define X first
#define Y second
#define pia 3.1415926536
#define mod 1000000007
#define mod2 998244353

#define ml map<ll,ll>
#define mll map<pll,ll>
#define vvl vector<vl>
#define vvi vector<vi>
#define letsh(a,b) a<<b
#define rigsh(a,b) a>>b 
mt19937 rng32(chrono::steady_clock::now().time_since_epoch().count()) ;
		bool sortbysec(const pair<int,int> &a, 
		      const pair<int,int> &b) 
		{ 
		    return (a.second < b.second); 
		} 	   
		
		  ll power(ll a,ll n)
		{
		ll ans=1;
		while(n)
		{
		if(n&1) ans=(ans*a)%mod;
		a=(a*a)%mod ;
		n=n>>1;
		 }
		 return ans;
		}
		ll power2(ll a,ll n)
		{
		ll ans =1 ;
		while(n)
		{
			if(n&1) ans =(ans*a) ;
			a = (a*a) ;
			n =n>>1 ;
		  }
		  return ans ;
		}
		ll lcm(ll a, ll b)
		{
		       return a / __gcd(a, b) * b;
		}
#define N 100006
vector<vector<int> >  dp  ;
vector<vector<int> > vis ;
vector<vector<char> > a ;int n,m  ;int st,st1 ,en,en1 ;
 vll dir({{-1,0} ,{0,-1} ,{1,0} ,{0,1}}) ; 
 bool inside(int x, int y)
       {
        	return 1 <= min(x, y) && x <=n && y <=m ;
       }
	void solve()
	    {
	    	cin>>n>>m ;
	    	a.resize(n+1) ;f(i,1,n+1) a[i].resize(m+1) ;
	        dp.resize(n+1) ;f(i,1,n+1) dp[i].resize(m+1,mod ) ;
			cin>>st>>st1>>en>>en1 ;
		 	f(i,1,n+1) f(j,1,m+1) cin>>a[i][j] ;
		 	deque<pair<int,int> > q ;q.pb({st,st1}) ;
		 	dp[st][st1] =0 ;
		   while(!q.empty())
		   {
		   	pair<int,int> cur = q.front() ;q.pop_front(); 
		   	f(k,0,4)
		   	{
		   		
		   		int x = cur.X -dir[k].X ,y  = cur.Y -dir[k].Y ;
		   		if(inside(x,y) && a[x][y] != '#' && dp[x][y] > dp[cur.X][cur.Y]) 
		   		{
		   			q.push_front({x,y}) ;dp[x][y] = dp[cur.X][cur.Y] ;
			    }
			   }
			   int i =cur.X ,j = cur.Y ;
			   f(x,i-2 ,i+3)
			   {
			   	f(y,j-2 ,j+3)
			   	{
			   		if(inside(x,y) && a[x][y] != '#' && dp[x][y] > dp[i][j] +1)
			   		{
			   			q.push_back({x,y}) ;dp[x][y] = 1+ dp[i][j] ;
					}
				   }
			   }
	} 
		   if(dp[en][en1] == mod) cout<<-1<<endl ;
		   else cout<<dp[en][en1]<<endl ;
		  }
			  int main() 
	  	{
	    SPEED
	     ll t  =1 ;
	     while(t--) solve() ;
	    }

Measured memory_bytes: 8620