#include<bits/stdc++.h>
#include<atcoder/all>
#define rep(i,b) for(int i=0;i<b;i++)
#define rrep(i,b) for(int i=b-1;i>=0;i--)
#define rep1(i,b) for(int i=1;i<b;i++)
#define repx(i,x,b) for(int i=x;i<b;i++)
#define rrepx(i,x,b) for(int i=b-1;i>=x;i--)
#define fore(i,a) for(auto i:a)
#define fore1(i,a) for(auto &i:a)
#define rng(x) (x).begin(), (x).end()
#define rrng(x) (x).rbegin(), (x).rend()
#define sz(x) ((int)(x).size())
#define pb push_back
#define fi first
#define se second
#define pcnt __builtin_popcountll

using namespace std;
using namespace atcoder;

using ll = long long;
using ld = long double;
template<typename T> using mpq = priority_queue<T, vector<T>, greater<T>>;
template<typename T> bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<typename T> bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }
template<typename T> ll sumv(const vector<T>&a){ll res(0);for(auto&&x:a)res+=x;return res;}
bool yn(bool a) { if(a) {cout << "Yes" << endl; return true;} else {cout << "No" << endl; return false;}}
#define dame { cout << "No" << endl; return;}
#define dame1 { cout << -1 << endl; return;}
#define deb(x,y) cout << x << " " << y << endl;
#define debp(p) cout << p.fi << " " << p.se << endl;
#define out cout << ans << endl;
#define outd cout << fixed << setprecision(20) << ans << endl;
#define outm cout << ans.val() << endl;
#define outv fore(yans , ans) cout << yans << "\n";
#define outdv fore(yans , ans) cout << yans.val() << "\n";
#define showv(v) {fore(vy , v) {cout << vy << " ";} cout << endl;}
#define showv2(v) fore(vy , v) cout << vy << "\n";
#define showvm(v) {fore(vy , v) {cout << vy.val() << " ";} cout << endl;}
#define showvm2(v) fore(vy , v) cout << vy.val() << "\n";
using pll = pair<ll,ll>;using pil = pair<int,ll>;using pli = pair<ll,int>;using pii = pair<int,int>;using pdd = pair<ld,ld>;
using tp = tuple<int ,int ,int>;
using vi = vector<int>;using vd = vector<ld>;using vl = vector<ll>;using vs = vector<string>;using vb = vector<bool>;
using vpii = vector<pii>;using vpli = vector<pli>;using vpll = vector<pll>;using vpil = vector<pil>;
using vvi = vector<vector<int>>;using vvl = vector<vector<ll>>;using vvs = vector<vector<string>>;using vvb = vector<vector<bool>>;
using vvpii = vector<vector<pii>>;using vvpli = vector<vector<pli>>;using vvpll = vector<vpll>;using vvpil = vector<vpil>;
using mint = modint998244353;
using vm = vector<mint>;
using vvm = vector<vector<mint>>;
vector<int> dx={1,0,-1,0,1,1,-1,-1},dy={0,1,0,-1,1,-1,1,-1};
ll gcd(ll a, ll b) { return a?gcd(b%a,a):b;}
ll lcm(ll a, ll b) { return a/gcd(a,b)*b;}
#define yes {cout <<"Yes"<<endl;}
#define yesr { cout <<"Yes"<<endl; return;}
#define no {cout <<"No"<<endl;}
#define nor { cout <<"No"<<endl; return;}
const double eps = 1e-10;
const ll LINF = 1001002003004005006ll;
const int INF = 1001001001;
#ifdef MY_LOCAL_DEBUG
#define show(x) cerr<<#x<<" = "<<x<<endl
#define showp(p) cerr<<#p<<" = "<<p.fi<<" : "<<p.se<<endl
#define show2(x,y) cerr<<#x<<" = "<<x<<" : "<<#y<<" = "<<y<<endl
#define show3(x,y,z) cerr<<#x<<" = "<<x<<" : "<<#y<<" = "<<y<<" : "<<#z<<" = "<<z<<endl
#define show4(x,y,z,x2) cerr<<#x<<" = "<<x<<" : "<<#y<<" = "<<y<<" : "<<#z<<" = "<<z<<" : "<<#x2<<" = "<<x2<<endl
#define test(x) cout << "test" << x << endl
#else
#define show(x)
#define showp(p)
#define show2(x,y)
#define show3(x,y,z)
#define show4(x,y,z,x2)
#define test(x)
#endif

struct edge{
    int from,to;
    ll cost;

    edge(int from_=0,int to_=0,ll cost_=0) : from(from_),to(to_),cost(cost_) {}
};

void solve(){
    int h,w; cin>>h>>w;
    int sx,sy,gx,gy; cin>>sx>>sy>>gx>>gy;
    sx--;
    sy--;
    gx--;
    gy--;
    vs s(h);
    rep(i,h) cin>>s[i];

    vvi v(w);

    rep(i,w){
        rep(j,h) if (s[j][i] != '#') v[i].pb(j);
    }

    int n = h * w;

    vector<vector<edge>> e(n);

    rep(i,h) rep(j,w){
        int n1 = i * w + j;
        repx(k,-1,2){
            int nj = j+k*2;
            int nj_sub = j+k;
            if (0 > nj_sub || nj_sub >= w) continue; 
            if (abs(k) != 0){
                auto sub = upper_bound(rng(v[nj_sub]) , i+1);
                if (sub != v[nj_sub].begin()){
                    sub--;
                    int tmp = *sub*w + nj_sub;
                    e[n1].pb(edge(n1,tmp,0));
                    if (0 > nj || nj >= w) continue;
                    int en = max(0 , i - *sub);
                    rep1(kk,3){
                        auto it = upper_bound(rng(v[nj]) , *sub+1+en/kk);
                        if (it != v[nj].begin()){
                            it--;
                            tmp = *it * w + nj;
                            e[n1].pb(edge(n1,tmp,2-kk));
                        }
                    }

                }
            }else{
                bool ok = false;
                rep(kk,2){
                    if (ok) continue;
                    int nj2 = j+2*kk-1;
                    if (0 > nj2 || nj2 >= w) continue; 
                    auto it = upper_bound(rng(v[nj2]) , i+1);
                    if (it != v[nj2].begin() && i+1 < h && s[i+1][j] != '#'){
                        int tmp = (i+1) * w + j;
                        e[n1].pb(edge(n1,tmp,1));
                        ok = true;
                    }
                }
            }
        } 
    }

    vector<int> dist(n,INF);
    mpq<pii> q;
    
    int st = sx*w + sy;
    dist[st] = 0;
    q.push({dist[st] , st});
    
    while(!q.empty()){
        pii p = q.top();
        q.pop();
        int dist_dum = p.first;
        int from = p.second;
    
        if (dist[from] < dist_dum) continue;
    
        fore(ey , e[from]){
            int to = ey.to;
            int cost = ey.cost;
    
            if (chmin(dist[to] , dist_dum + cost)){
                q.push({dist[to] , to});
            }
        }
    }

    int ans = dist[gx * w + gy];
    if (ans == INF) ans = -1;

    out;




    return;
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);

    int t = 1;
    //cin>>t;

    rep(i,t){
        solve();
    }

    return 0;
}