#include <iostream>
#include <string>
#include <algorithm>
#include <vector>
#include <queue>
#include <map>
#include <unordered_map>
#include <set>
#include <unordered_set>
#include <cmath>
#include <numeric>
#include <iomanip>
#include <stack>
#include <complex>
#include <functional>
#include <tuple>

using namespace std;

#define Rep(i,a,b) for(ll i = a; i < b; ++i)
#define rep(i,b) Rep(i,0,b)
#define allof(a) (a).begin(), (a).end()

#define Yes(q) ((q) ? "Yes" : "No")
#define YES(q) ((q) ? "YES" : "NO")
#define Possible(q) ((q) ? "Possible" : "Impossible")
#define POSSIBLE(q) ((q) ? "POSSIBLE" : "IMPOSSIBLE")

using ll = long long;

constexpr int inf = 1e9 + 7;
constexpr ll infll = 1ll << 60ll;
constexpr ll mod = 1e9 + 7;
// 0~3までは右下左上 4~7までは斜め
constexpr int dx[] = { 1, 0, -1, 0, 1, -1 };
constexpr int dy[] = { 0, 1, 0, -1, 1, 1 };

namespace {
    template<typename T> bool chmax(T& a, T b) { if (a < b) { a = b; return true; } return false; }
    template<typename T> bool chmin(T& a, T b) { if (a > b) { a = b; return true; } return false; }

    // 標準出力
    void Write(long long x, const char* end = "\n") { std::cout << x << end; }
    template <typename T> void Write(const T& x, const char* end = "\n") { std::cout << x << end; }
    template <typename T, typename U> void Write(const T& x, const U& y, const char* end = "\n") { std::cout << x << " " << y << end; }
    template <typename T, typename U, typename V> void Write(const T& x, const U& y, const V& z, const char* end = "\n") { std::cout << x << " " << y << " " << z << end; }
    //template <typename... Args> void Write(Args const&... args) { bool a = true; for (auto const& x : { args... }) { if (a) a = false; else std::cout << " "; std::cout << x; } std::cout << "\n"; }
    template <typename T> void Write(const std::vector<T>& x, const char* sep = " ", const char* end = "\n") { for (std::size_t i = 0, sz = x.size(); i < sz; ++i) { std::cout << x[i] << (i == sz - 1 ? end : sep); } }
    template <typename T> void Write(const std::vector<std::vector<T>>& x, const char* sep = " ", const char* end = "\n") { for (auto v : x) Write(v, sep, end); }

    // 標準入力
    struct Read {
        std::size_t szi, szj;
        Read(std::size_t _szi = 1, std::size_t _szj = 1) : szi(_szi), szj(_szj) {}
        template <typename T> operator T () const { T a; std::cin >> a; return a; }
        template <typename T> operator std::vector<T>() const { std::vector<T> a(szi); for (std::size_t i = 0; i < szi; ++i) std::cin >> a[i]; return a; }
        template <typename T> operator std::vector<std::vector<T>>() const {
            std::vector<std::vector<T>> a(szi, std::vector<T>(szj));
            for (std::size_t i = 0; i < szi; ++i) for (std::size_t j = 0; j < szj; ++j) cin >> a[i][j]; return a;
        }
        template <typename T, typename U> operator std::vector<std::pair<T, U>>() const {
            std::vector<std::pair<T, U>> a(szi);
            for (std::size_t i = 0; i < szi; ++i) std::cin >> a[i].first >> a[i].second; return a;
        }
    };
    struct Reads {
        template <typename T> Reads(T& a) { std::cin >> a; }
        template <typename T, typename U> Reads(T& a, U& b) { std::cin >> a >> b; }
        template <typename T, typename U, typename V> Reads(T& a, U& b, V& c) { std::cin >> a >> b >> c; }
        template <typename T, typename U, typename V, typename W> Reads(T& a, U& b, V& c, W& d) { std::cin >> a >> b >> c >> d; }
    };

    Read read;

    struct Edge {
        ll from; // 移動前のノード
        ll to; // 移動先のノード
        ll cost; // 辺のコスト
        ll hoge; // 任意変更 いらないかも

        Edge() = default;
        Edge(ll _to) : from(-1), to(_to), cost(1), hoge(-1) {};
        Edge(ll _to, ll _cost) : from(-1), to(_to), cost(_cost), hoge(-1) {};
        Edge(ll _from, ll _to, ll _cost) : from(_from), to(_to), cost(_cost), hoge(-1) {};
        Edge(ll _from, ll _to, ll _cost, ll _hoge) : from(_from), to(_to), cost(_cost), hoge(_hoge) {};
        bool operator< (const Edge& rhs) const {
            return cost < rhs.cost;
        }
        bool operator> (const Edge& rhs) const {
            return cost > rhs.cost;
        }
        bool operator==(const Edge& rhs) const {
            if (from != rhs.from) return false;
            if (to != rhs.to) return false;
            if (cost != rhs.cost) return false;
            if (hoge != rhs.hoge) return false;
            return true;
        }
        bool operator!=(const Edge& rhs) const {
            if (from != rhs.from) return true;
            if (to != rhs.to) return true;
            if (cost != rhs.cost) return true;
            if (hoge != rhs.hoge) return true;
            return false;
        }
    };

    using Graph = vector<vector<Edge>>;

    // ダイクストラ法 O(ElogV)
    vector<ll> dijkstra(ll start, const Graph& G) {
        vector<ll> dist(G.size(), infll);
        // 辺のコストが小さい順に取り出す　場合に応じて変更
        priority_queue<Edge, vector<Edge>, greater<Edge>> que;
        //queue<Edge> que; // コストがすべて1の場合は普通のbfsにする コメントアウトしよう

        dist[start] = 0; // dist[i] := start->iまでの最短距離
        que.push(Edge(start, 0));

        while (!que.empty()) {
            ll cost, u; // 今までにかかった時間　現在の頂点
            cost = que.top().cost, u = que.top().to;
            //cost = que.front().cost, u = que.front().to;
            que.pop();
            if (dist[u] < cost) continue;
            for (auto& e : G[u]) {
                ll v = e.to;
                ll new_cost = cost + e.cost;

                if (dist[v] <= new_cost) continue;

                dist[v] = new_cost;
                que.push(Edge(v, new_cost));
            }
        }
        return dist;
    }
}

int main() {

    int h, w; Reads(h, w);
    int ch, cw; Reads(ch, cw);
    --ch, --cw;
    int dh, dw; Reads(dh, dw);
    --dh, --dw;
    vector<string> s = Read(h);

    Graph G(h * w);

    int cnt = 0;
    vector<vector<int>> toNode(h, vector<int>(w, 0));

    rep(y, h) {
        rep(x, w) {
            toNode[y][x] = cnt++;
        }
    }

    rep(y, h) {
        rep(x, w) {
            if (s[y][x] == '#') continue;

            rep(k, 4) {
                int ty = y + dy[k];
                int tx = x + dx[k];

                if (ty < 0 || ty >= h) continue;
                if (tx < 0 || tx >= w) continue;
                if (s[ty][tx] == '#') continue;
                G[toNode[y][x]].emplace_back(toNode[ty][tx], 0);
            }

            // ワープ
            for (int dx = -2; dx <= 2; ++dx) {
                for (int dy = -2; dy <= 2; ++dy) {
                    if (dx == 0 && dy == 0) continue;

                    int ty = y + dy;
                    int tx = x + dx;

                    if (ty < 0 || ty >= h) continue;
                    if (tx < 0 || tx >= w) continue;
                    if (s[ty][tx] == '#') continue;
                    G[toNode[y][x]].emplace_back(toNode[ty][tx], 1);
                }
            }
        }
    }

    auto dist = dijkstra(toNode[ch][cw], G);

    ll ans = dist[toNode[dh][dw]];
    if (ans == infll) ans = -1;
    Write(ans);

    return 0;
}


Measured memory_bytes: 344556