#include "bits/stdc++.h"
#define rep(i, j) for (int i = 0; i < j; i++)
#define srep(i, j, k) for (int i = j; i < k; i++)
using namespace std;
using ll = long long;
using P = pair<int, int>;
using ull = unsigned long long;

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

//エラトステネスの篩
vector<int> estora(vector<int> num) {
    int sel = 0;
    while (sel < num.size()) {
        int d = num[sel];
        for (int i = 0; i < num.size(); i++) {
            if (num[i] % d == 0 && num[i] != d && d != 1) {
                num.erase(num.begin() + i);
                i--;
            }
        }
        sel++;
    }
    return num;
}
/*ライブラリ最大公約数*/
//ユーグリッドの互除法
int gcd(int x, int y) {
    int num[3];
    num[0] = (x > y) ? x : y;
    num[1] = (x <= y) ? x : y;
    num[2] = num[0] % num[1];

    while (num[2]) {
        num[0] = num[1];
        num[1] = num[2];
        num[2] = num[0] % num[1];
    }

    return num[1];
}

/*素因数分解*/
//自作ライブラリ
//iを常に素数にしておかないとうまくできない&&計算量ヤバイ
//エストラネスの篩で素数を振るっておく必要性がありそう
vector<ll> fac(ll n, vector<ll> num) {
    ll kazu = n;
    for (int i = 2; i <= n; i++) {
        while (1) {
            if (kazu % i != 0) break;

            kazu /= i;
            num[i]++;
        }
    }
    if (kazu == n && n != 1)
        num[n]++;
    return num;
    int ans = 0;
    if (kazu != 1) ans++;
    for (int i = 2; i <= sqrt(n); i++) {
        for (int j = 1; j <= num[i]; j++) {
            num[i] -= j;
            ans++;
        }
    }
    return num;
}
const int INF = 1001001001;

//mint用の定数 (10の9乗 + 7)
const int mod = 1000000007;

struct mint {
    ll x; // typedef long long ll;
    mint(ll x = 0) :x((x% mod + mod) % mod) {}
    mint operator-() const { return mint(-x); }
    mint& operator+=(const mint a) {
        if ((x += a.x) >= mod) x -= mod;
        return *this;
    }
    mint& operator-=(const mint a) {
        if ((x += mod - a.x) >= mod) x -= mod;
        return *this;
    }
    mint& operator*=(const mint a) { (x *= a.x) %= mod; return *this; }
    mint operator+(const mint a) const { return mint(*this) += a; }
    mint operator-(const mint a) const { return mint(*this) -= a; }
    mint operator*(const mint a) const { return mint(*this) *= a; }
    mint pow(ll t) const {
        if (!t) return 1;
        mint a = pow(t >> 1);
        a *= a;
        if (t & 1) a *= *this;
        return a;
    }

    // for prime mod
    mint inv() const { return pow(mod - 2); }
    mint& operator/=(const mint a) { return *this *= a.inv(); }
    mint operator/(const mint a) const { return mint(*this) /= a; }
};
istream& operator>>(istream& is, const mint& a) { return is >> a.x; }
ostream& operator<<(ostream& os, const mint& a) { return os << a.x; }

int main() {
    int h, w;
    cin >> h >> w;
    P s, g;
    int sh, sw, gh, gw;
    cin >> sh >> sw >> gh >> gw;
    sw--; sh--; gw--; gh--;
    s.first = sh; s.second = sw;
    g.first = gh; g.second = gw;

    vector<string> ss(h);
    rep(i, h) cin >> ss[i];

    deque<P> masu;
    vector<vector<int> > map(h, vector<int> (w, -1));
    map[s.first][s.second] = 0;
    masu.push_front(s);
    while (!masu.empty()) {
        P current = masu.front(); masu.pop_front();
        vector<int> vec = { -2, -1, 0, 1, 2 };
        rep(i, vec.size()) {
            rep(j, vec.size()) {
                if (!(current.first + vec[i] >= 0 && current.first + vec[i] < h && current.second + vec[j] >= 0 && current.second + vec[j] < w)) continue;
                int cost = 0;
                if (abs(vec[i]) + abs(vec[j]) >= 2)
                    cost = 1;
                if (map[current.first + vec[i]][current.second + vec[j]] <= map[current.first][current.second] + cost && map[current.first + vec[i]][current.second + vec[j]] != -1) continue;
                if (ss[current.first + vec[i]][current.second + vec[j]] == '#') continue;

                map[current.first + vec[i]][current.second + vec[j]] = cost + map[current.first][current.second];
                if (cost == 0)
                    masu.push_front(P(current.first + vec[i], current.second + vec[j]));
                else
                    masu.push_back(P(current.first + vec[i], current.second + vec[j]));
            }
        }
    }
    cout << map[g.first][g.second] << endl;
    return 0;
}


Measured memory_bytes: 9476