#include <bits/stdc++.h>
using namespace std;
#define rep(i, n)  for(long long i=0;i<(long long)(n);i++)
#define REP(i,k,n) for(long long i=k;i<(long long)(n);i++)
#define pb emplace_back
#define lb(v,k) (lower_bound(all(v),(k))-v.begin())
#define ub(v,k) (upper_bound(all(v),(k))-v.begin())
#define fi first
#define se second
#define pi M_PI
#define PQ(T) priority_queue<T>
#define SPQ(T) priority_queue<T,vector<T>,greater<T>>
#define dame(a) {out(a);return 0;}
#define decimal cout<<fixed<<setprecision(15);
#define all(a) a.begin(),a.end()
#define rsort(a) {sort(all(a));reverse(all(a));}
#define dupli(a) {sort(all(a));a.erase(unique(all(a)),a.end());}
typedef long long ll;
typedef pair<ll,ll> P;
typedef tuple<ll,ll,ll> PP;
typedef tuple<ll,ll,ll,ll> PPP;
using vi=vector<ll>;
using vvi=vector<vi>;
using vvvi=vector<vvi>;
using vvvvi=vector<vvvi>;
using vp=vector<P>;
using vvp=vector<vp>;
using vb=vector<bool>;
using vvb=vector<vb>;
const ll inf=1001001001001001001;
const ll INF=1001001001;
const ll mod=1000000007;
const double eps=1e-10;
template<class T> bool chmin(T&a,T b){if(a>b){a=b;return true;}return false;}
template<class T> bool chmax(T&a,T b){if(a<b){a=b;return true;}return false;}
template<class T> void out(T a){cout<<a<<'\n';}
template<class T> void outp(T a){cout<<'('<<a.fi<<','<<a.se<<')'<<'\n';}
template<class T> void outvp(T v){rep(i,v.size())cout<<'('<<v[i].fi<<','<<v[i].se<<')';cout<<'\n';}
template<class T> void outvvp(T v){rep(i,v.size())outvp(v[i]);}
template<class T> void outv(T v){rep(i,v.size()){if(i)cout<<' ';cout<<v[i];}cout<<'\n';}
template<class T> void outvv(T v){rep(i,v.size())outv(v[i]);}
template<class T> bool isin(T x,T l,T r){return (l)<=(x)&&(x)<=(r);}
template<class T> void yesno(T b){if(b)out("yes");else out("no");}
template<class T> void YesNo(T b){if(b)out("Yes");else out("No");}
template<class T> void YESNO(T b){if(b)out("YES");else out("NO");}
template<class T> void outset(T s){auto itr=s.begin();while(itr!=s.end()){if(itr!=s.begin())cout<<' ';cout<<*itr;itr++;}cout<<'\n';}
void outs(ll a,ll b){if(a>=inf-100)out(b);else out(a);}
ll gcd(ll a,ll b){if(b==0)return a;return gcd(b,a%b);}
ll modpow(ll a,ll b){ll res=1;a%=mod;while(b){if(b&1)res=res*a%mod;a=a*a%mod;b>>=1;}return res;}
ll f(ll a,ll b){
    if(a==b)return 5;
    if(a+b==3)return 4;
    if(a<=3)return a;
    if(a==4)return b;
    return 3-b;
}
int main(){
    ll h,w;cin>>h>>w;assert(2<=h&&h<=1000);assert(2<=w&&w<=1000);
    ll sx,sy;cin>>sx>>sy;assert(1<=sx&&sx<=h);assert(1<=sy&&sy<=w);
    ll gx,gy;cin>>gx>>gy;assert(1<=gx&&gx<=h);assert(1<=gy&&gy<=w);
    vvb v(h+2,vb(w+2,false));
    rep(i,h){
        string s;cin>>s;assert(s.size()==w);
        rep(j,w){
            assert(s[j]=='.'||s[j]=='#');
            if(s[j]=='.')v[i+1][j+1]=true;
        }
    }assert(v[gx][gy]);assert(v[sx][sy]);
    queue<pair<P,ll>> que;
    que.emplace(P(sx,sy),4);
    vvvi dp(h+2,vvi(w+2,vi(6,inf)));dp[sx][sy][4]=0;
    vi dx={1,0,0,-1},dy={0,1,-1,0};
    while(!que.empty()){
        auto t=que.front();que.pop();
        rep(i,4)if(v[t.fi.fi+dx[i]][t.fi.se+dy[i]]&&chmin(dp[t.fi.fi+dx[i]][t.fi.se+dy[i]][f(t.se,i)],dp[t.fi.fi][t.fi.se][t.se]+1))que.emplace(P(t.fi.fi+dx[i],t.fi.se+dy[i]),f(t.se,i));
    }
    outs(dp[gx][gy][4],-1);
}