#include <bits/stdc++.h>
#pragma GCC optimize("Ofast")
using namespace std;
using std::cout;
using std::cin;
using std::endl;
using ll=long long;
using ld=long double;
ll ILL=2167167167167167167;
const int INF=2100000000;
const ll mod=998244353;
#define rep(i,a) for (ll i=0;i<a;i++)
#define all(p) p.begin(),p.end()
template<class T> using _pq = priority_queue<T, vector<T>, greater<T>>;
template<class T> ll LB(vector<T> &v,T a){return lower_bound(v.begin(),v.end(),a)-v.begin();}
template<class T> ll UB(vector<T> &v,T a){return upper_bound(v.begin(),v.end(),a)-v.begin();}
template<class T> bool chmin(T &a,const T &b){if(a>b){a=b;return 1;}else return 0;}
template<class T> bool chmax(T &a,const T &b){if(a<b){a=b;return 1;}else return 0;}
template<class T> void So(vector<T> &v) {sort(v.begin(),v.end());}
template<class T> void Sore(vector<T> &v) {sort(v.begin(),v.end(),[](T x,T y){return x>y;});}
void yneos(bool a){if(a) cout<<"Yes\n"; else cout<<"No\n";}
template<class T> void vec_out(vector<T> &p){for(int i=0;i<(int)(p.size());i++){if(i) cout<<" ";cout<<p[i];}cout<<"\n";}
template<class T> T min(vector<T> &a){assert(!a.empty());T ans=a[0];for(auto &x:a) chmin(ans,x);return ans;}
template<class T> T max(vector<T> &a){assert(!a.empty());T ans=a[0];for(auto &x:a) chmax(ans,x);return ans;}



void solve();
// oddloop
int main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	
	int t=1;
	//cin>>t;
	rep(i,t) solve();
}

void solve(){
	int H,W;
	cin>>H>>W;
	int sx,sy,gx,gy;
	cin>>sx>>sy>>gx>>gy;
	sx--,sy--,gx--,gy--;
	vector<string> S(H);
	vector<vector<int>> p(W);
	rep(i,H){
		cin>>S[i];
		rep(j,W){
			if(S[i][j]=='.') p[j].push_back(i);
		}
	}
	rep(j,W) p[j].push_back(INF);
	vector<vector<int>> seen(H,vector<int>(W,INF));
	vector<pair<int,int>> order={{sx,sy}};
	vector<pair<int,int>> n_order;
	int dist=-1;
	while(!order.empty()){
		dist++;
		int ind=0;
		while(ind!=(int)(order.size())){
			int x,y;
			tie(x,y)=order[ind];
			ind++;
			while(x!=-1&&seen[x][y]>dist){
				seen[x][y]=dist;
				if(S[x][y]=='.'){
					int ne=min(H-1,x+1);
					if(y!=0){
						if(p[y-1][0]<x){
							int c=p[y-1][LB(p[y-1],x)-1];
							int a=min(H-1,c+1+(x-c)/2);
							n_order.push_back({ne,y});
							if(y!=1){
								n_order.push_back({ne,y-2});
								order.push_back({a,y-2});
							}
						}
						order.push_back({ne,y-1});
					}
					if(y!=W-1){
						if(p[y+1][0]<x){
							int c=p[y+1][LB(p[y+1],x)-1];
							int a=min(H-1,c+1+(x-c)/2);
							n_order.push_back({ne,y});
							if(y!=W-2){
							n_order.push_back({ne,y+2});
							order.push_back({a,y+2});
							}
						}
						order.push_back({ne,y+1});
					}
				}
				x--;
			}
		}
		order=n_order;
		n_order.clear();
	}
	/*
	rep(i,H){
		rep(j,W){
			if(seen[i][j]==INF) cout<<"# ";
			else cout<<seen[i][j]<<" ";
		}
		cout<<"\n";
	}*/
	if(seen[gx][gy]==INF) cout<<"-1\n";
	else cout<<seen[gx][gy]<<"\n";
}