#include <bits/stdc++.h>
	#include <cstdio>
	#include <cstring>
	#include <cmath>
	#include <cstring>
	#include <chrono>
	#include <complex>
	#define endl "\n"	
	typedef long long LL;
	#define ld long double
	#define ll long long int
	#define vi vector<int>
	#define vll vector<ll>
	#define vvi vector < vi >
	#define pii pair<int,int>
	#define pll pair<long long, long long>
	#define mod 1000000007
	#define mod2 998244353
	#define INFINITE 1000000000000000001;
	#define all(c) c.begin(),c.end()
	#define sz(v) ((ll)(v).size())
	#define mp(x,y) make_pair(x,y)
	#define mem(a,val) memset(a,val,sizeof(a))
	#define eb emplace_back
	#define pb push_back
	#define f first
	#define s second
	#define dbg(a) cout<<#a<<" --> "<<(a)<<"\n";
	#define forn(i,n) for (ll i=0; i<(n); ++i)
	#define fornd(i,n) for (ll i=(n)-1; i>=0; --i)	
	#define forab(i,a,b) for (ll i=(a); i<=(b); ++i)
	#define read(a) ll a; cin >> a;
	#define reads(s) string s; cin >> s;
	#define readb(a, b) ll a, b; cin >> a >> b;
	#define readc(a, b, c) ll a, b, c; cin >> a >> b >> c;
	#define readarr(a, n) int a[(n) + 1] = {}; forab(i, 0, (n-1)) {cin >> a[i];}
	#define readmat(a, n, m) int a[n + 1][m + 1] = {}; forab(i, 1, n) {forab(j, 1, m) cin >> a[i][j];}
	#define readv(A,n) vll A(n,0); forn(i,n) cin>>A[i]; 
	#define print(a) cout << a << endl;
	#define printarr(a, n) forab (i, 1, n) cout << a[i] << " "; cout << endl;
	#define printv(v) for (int i: v) cout << i << " "; cout << endl;
	#define printmat(a, n, m) forab(i, 1, n) {forab (j, 1, m) cout << a[i][j] << " "; cout << endl;}
	#define precision(a) cout<<fixed<<setprecision(a);
	#define INF (1e18+5)
	#define inf (1e9+5)
	int dx[4] = { 0, 0, 1, -1 };
	int dy[4] = { 1, -1, 0, 0 };
	// 8-directions
	//int dx[]={1,1,1,0,0,-1,-1,-1};
	//int dy[]={-1,0,1,-1,1,-1,0,1};
	#define fast_io ios_base::sync_with_stdio(false),cin.tie(NULL),cout.tie(NULL)
	using namespace std;
	int begtime = clock();
	mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
	mt19937_64 rngb(chrono::steady_clock::now().time_since_epoch().count()); // can give negative values too
	bool isPowerOfTwo(int x) {
    return x && (!(x & (x - 1)));
	}
	int takemod(int x) {
    return (x % mod + mod) % mod;
	}
 
	int fpow(int base, int power, int MOD) {
    int result = 1;
    base = base % MOD;
    while (power) {
        if (power & 1)
            result = (result * base) % MOD;
        base = (base * base) % MOD;
        power = power >> 1;
    }
    return result;
	}
 
	int modinv(int x) {return fpow(x, mod - 2, mod);}
	ll n,m,sx,sy,fx,fy; 		
	ll A[2000][2000];
	ll dist[2000][2000];
	bool valid(ll x,ll y)
	{
		return (x>=1&&y>=1&&x<=n&&y<=m);
	}
	void bfs()
	{
		mem(dist,0);
		dist[sx][sy]=1;
		deque<pll> pq;
		pq.push_front({sx,sy});

		while(!pq.empty())
		{
			pll temp=pq.front();
			pq.pop_front();
			ll di=temp.f;
			ll dj=temp.s;
			//cout<<temp.f<<" "<<temp.s<<endl;
			for(ll i=temp.f-2;i<=temp.f+2;i++)
			{
				for(ll j=temp.s-2;j<=temp.s+2;j++)
				{
					//cout<<i<<" "<<j<<endl;
					if(valid(i,j)&&A[i][j]==1&&(dist[i][j]==0||dist[i][j]>dist[temp.f][temp.s]+1))
					{
						dist[i][j]=dist[temp.f][temp.s]+1;
						pq.push_back({i,j});
					}
				}
			}
			forn(i,4)
			{
				di=temp.f+dx[i];
				dj=temp.s+dy[i];
				if(valid(di,dj)&&A[di][dj]==1&&(dist[di][dj]==0||dist[di][dj]>dist[temp.f][temp.s]))
				{
					//cout<<di<<" "<<dj<<endl;
					dist[di][dj]=dist[temp.f][temp.s];
					pq.push_front({di,dj});
				}
			}


		}
	}
	void solve()
	{	
		cin>>n>>m>>sx>>sy>>fx>>fy;
		string x;
		forn(i,n+2)
		{
			forn(j,m+2)
			{
				A[i][j]=0;
				dist[i][j]=0;	
			}
		}
		forn(i,n)
		{
			cin>>x;
			forn(j,m)
			{
				if(x[j]=='.')A[i+1][j+1]=1;
				else A[i+1][j+1]=0;

			}
		}
		bfs();
		// forab(i,1,n)
		// {
		// 	forab(j,1,m)
		// 	{
		// 		cout<<A[i][j]<<" ";
		// 	}
		// 	cout<<endl;
		// }
		// forab(i,1,n)
		// {
		// 	forab(j,1,m)
		// 	{
		// 		cout<<dist[i][j]<<" ";
		// 	}
		// 	cout<<endl;
		// }
		if(A[sx][sy]==0||A[fx][fy]==0||dist[fx][fy]==0)
		{
			cout<<-1<<endl;
		}
		else
			cout<<dist[fx][fy]-1<<endl;

	}
	int main()
	{	
		#ifndef ONLINE_JUDGE
		freopen("input.txt","r",stdin);
		freopen("output.txt","w",stdout);
		#endif
		fast_io;
		int T=1;
		//cin>>T;
		// cin.ignore(); must be there when using getline(cin, s)
		while(T--)
		{
			solve();
		}
		#ifndef ONLINE_JUDGE
    		cerr << "Time elapsed: " << (clock() - begtime)*1000/CLOCKS_PER_SEC << " ms\n\n";
    		#endif
		return 0;
	}

	
	
	
	

Measured memory_bytes: 46776