#include<bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef unsigned long long ul;
typedef unsigned int ui;
typedef pair<int, int>P;
typedef pair<ll, ll> LP;
typedef long double ld;
typedef pair<ld, ld> LDP;
typedef vector<vector<ll> > mat;
typedef vector<ll> vec;
#define rep(i,n) for(int i=0;i<n;i++)
#define per(i,n) for(int i=n-1;i>=0;i--)
#define Rep(i,sta,n) for(int i=sta;i<n;i++)
#define rep1(i,n) for(int i=1;i<=n;i++)
#define per1(i,n) for(int i=n;i>=1;i--)
#define Rep1(i,sta,n) for(int i=sta;i<=n;i++)
#define all(v) (v).begin(),(v).end()
const ll mod = 1000000007;
const ll INF = mod * mod;
const ld eps = 1e-12;
const ld pi = acos(-1.0);
//int qp(int a,ll b){int ans=1;do{if(b&1)ans=1ll*ans*a%mo;a=1ll*a*a%mo;}while(b>>=1);return ans;}
ll qp(ll a,ll b,int mo){int ans=1;do{if(b&1)ans=1ll*ans*a%mo;a=1ll*a*a%mo;}while(b>>=1);return ans;}
ll gcd(ll a,ll b){return b?gcd(b,a%b):a;} // 最大公約数
ll lcm (ll a, ll b){return a/gcd(a,b)*b;} // 最小公倍数
int dx[4] = { 0,1,0,-1 };
int dy[4] = { 1,0,-1,0 };

template<typename T> istream &operator>>(istream &is, vector<T> &vec){ for (auto &v : vec) is >> v; return is; }
template<typename T> ostream &operator<<(ostream &os, const vector<T> &vec){ os << "["; for (auto v : vec) os << v << ","; os << "]"; return os; }
template<typename T> ostream &operator<<(ostream &os, const deque<T> &vec){ os << "deq["; for (auto v : vec) os << v << ","; os << "]"; return os; }
template<typename T> ostream &operator<<(ostream &os, const set<T> &vec){ os << "{"; for (auto v : vec) os << v << ","; os << "}"; return os; }
template<typename T> ostream &operator<<(ostream &os, const unordered_set<T> &vec){ os << "{"; for (auto v : vec) os << v << ","; os << "}"; return os; }
template<typename T> ostream &operator<<(ostream &os, const multiset<T> &vec){ os << "{"; for (auto v : vec) os << v << ","; os << "}"; return os; }
template<typename T> ostream &operator<<(ostream &os, const unordered_multiset<T> &vec){ os << "{"; for (auto v : vec) os << v << ","; os << "}"; return os; }
template<typename T1, typename T2> ostream &operator<<(ostream &os, const pair<T1, T2> &pa){ os << "(" << pa.first << "," << pa.second << ")"; return os; }
template<typename TK, typename TV> ostream &operator<<(ostream &os, const map<TK, TV> &mp){ os << "{"; for (auto v : mp) os << v.first << "=>" << v.second << ","; os << "}"; return os; }
template<typename TK, typename TV> ostream &operator<<(ostream &os, const unordered_map<TK, TV> &mp){ os << "{"; for (auto v : mp) os << v.first << "=>" << v.second << ","; os << "}"; return os; }
template<typename T> void ndarray(vector<T> &vec, int len) { vec.resize(len); }
template<typename T, typename... Args> void ndarray(vector<T> &vec, int len, Args... args) { vec.resize(len); for (auto &v : vec) ndarray(v, args...); }
template<typename T> bool chmax(T &m, const T q) { if (m < q) {m = q; return true;} else return false; }
template<typename T> bool chmin(T &m, const T q) { if (q < m) {m = q; return true;} else return false; }
template<typename T1, typename T2> pair<T1, T2> operator+(const pair<T1, T2> &l, const pair<T1, T2> &r) { return make_pair(l.first + r.first, l.second + r.second); }
template<typename T1, typename T2> pair<T1, T2> operator-(const pair<T1, T2> &l, const pair<T1, T2> &r) { return make_pair(l.first - r.first, l.second - r.second); }
template<typename T1, typename T2> pair<T1, T2> operator<(const pair<T1, T2> l, const pair<T1, T2> r) { return (l.first < r.first); }
template<typename T1, typename T2> pair<T1, T2> operator>(const pair<T1, T2> l, const pair<T1, T2> r) { return (l.first > r.first); }



void solve() {
    ll H,W; cin >> H >> W;
    ll Ch,Cw,Dh,Dw; cin >> Ch >> Cw >> Dh >> Dw; 
    Ch--; Cw--; Dh--; Dw--; 
    char c[H][W];
    rep(i,H){
        rep(j,W){
            cin >> c[i][j];
        }
    }

    struct edge { ll to, cost; };
    // typedef pair<long long, long long> LP; // firstは最短距離, secondは頂点の番号
    ll V = H*W;
    vector<edge> G[V];
    ll d[V];
    ll start = Ch*W + Cw;
    ll goal = Dh*W + Dw;

    rep(i,H){
        rep(j,W){
            if(c[i][j] == '#') continue;

            ll d[5] = {-2, -1, 0, 1, 2};
            rep(k,5){
                rep(l,5){
                    ll h = i + d[k];
                    ll w = j + d[l];
                    if(h<0 || h>=H || w<0 || w>=W)continue;
                    if(c[h][w]=='#') continue;

                    bool is0 = false;
                    rep(m,4){
                        if(d[k]==dx[m] && d[l]==dy[m])is0 = true;
                    }
                    edge e;
                    e.to = h*W + w;
                    e.cost = is0 ? 0 : 1;
                    G[i*W+j].push_back(e);
                }
            }
        }
    }


    deque<LP> dq;
    fill(d, d + V, INF);
    d[start] = 0;
    dq.push_front(LP(0,start));

    while(!dq.empty()) {
        LP p = dq.front();
        dq.pop_front();
        ll v = p.second;
        if(d[v] < p.first) continue;
        for(ll i = 0; i < G[v].size(); ++i) {
            edge e = G[v][i];
            if(d[e.to] > d[v] + e.cost) {
                d[e.to] = d[v] + e.cost;
                if(e.cost==0){
                    dq.push_front(LP(d[e.to], e.to));
                }
                else{
                    dq.push_back(LP(d[e.to], e.to));
                }
            }
        }
    }

    ll res = d[goal];
    if(res>=INF) res=-1;

    cout << res << endl;
}

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

    std::cout << fixed << setprecision(10);
    solve();
    return 0;
}


Measured memory_bytes: 175856