#include <iostream>
#include <string>
#include <cmath>
#include<algorithm>
#include<stack>
#include<queue>
#include<map>
#include<set>
#include<iomanip>
#define _USE_MATH_DEFINES
#include <math.h>
#include <functional>
#include<complex>
#include<cassert>
using namespace std;

#define rep(i,x) for(ll i=0;i<x;i++)
#define repn(i,x) for(ll i=1;i<=x;i++)

typedef long long ll;
const ll INF = 1e17;
const ll MOD = 1000000007;
const ll MAX = 4000001;
const long double eps = 1E-14;

ll max(ll a, ll b) {
	if (a > b) { return a; }
	return b;
}

ll min(ll a, ll b) {
	if (a > b) { return b; }
	return a;
}

ll gcd(ll a, ll b) {
	if (b == 0) { return a; }
	if (a < b) { return gcd(b, a); }
	return gcd(b, a % b);
}

ll lcm(ll a, ll b) {
	return a / gcd(a, b) * b;
}

struct edge {
	ll ind;
	ll fr;
	ll to;
	ll d;
};

class mint {
	long long x;
public:
	mint(long long 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 {
		mint res(*this);
		return res += a;
	}
	mint operator-(const mint& a) const {
		mint res(*this);
		return res -= a;
	}
	mint operator*(const mint& a) const {
		mint res(*this);
		return res *= 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 {
		mint res(*this);
		return res /= a;
	}

	friend ostream& operator<<(ostream& os, const mint& m) {
		os << m.x;
		return os;
	}
};

mint pw(mint a, ll b) {
	if (b == 0) { return 1; }
	mint ret = pw(a, b >> 1);
	ret *= ret;
	if (b & 1) { ret *= a; }
	return ret;
}

typedef vector<ll> vll;
typedef vector<vector<ll>> vvll;
typedef vector<vector<vector<ll>>> vvvll;

typedef vector<mint> vmint;
typedef vector<vector<mint>> vvmint;
typedef vector<vector<vector<mint>>> vvvmint;

/////////////////////////////////////
int main() {
	ll H, W;
	cin >> H >> W;
	ll ch, dh, cw, dw;
	cin >> ch >> cw >> dh >> dw;

	vector<vector<char>> s(H + 1, vector<char>(W + 1));
	repn(i, H)repn(j, W)cin >> s[i][j];

	vvll dis(H + 1, vll(W + 1, -1));

	queue<ll> qx, qy;
	queue<ll> qx2, qy2;
	qx.push(ch);
	qy.push(cw);
	dis[ch][cw] = 0;

	vll dx = { 1,-1,0,0 };
	vll dy = { 0,0,1,-1 };

	while (!qx.empty()) {

		while (!qx.empty()) {
			ll x = qx.front();
			ll y = qy.front();
			qx2.push(x);
			qy2.push(y);
			//cout << x << " " << y << " " << dis[x][y] << endl;
			qx.pop();
			qy.pop();
			rep(k, 4) {
				ll xx = x + dx[k];
				ll yy = y + dy[k];
				if (xx<=0 || yy<=0 || xx>H || yy>W) { continue; }
				if (dis[xx][yy] != -1) { continue; }
				if (s[xx][yy] == '#') { continue; }
				dis[xx][yy] = dis[x][y];
				qx.push(xx);
				qy.push(yy);
			}
		}

		while (!qx2.empty()) {
			ll x = qx2.front();
			ll y = qy2.front();
			qx2.pop();
			qy2.pop();

			rep(k, 5)rep(l, 5) {
				ll xx = x + k - 2;
				ll yy = y + l - 2;
				if (xx<=0 || yy<=0 || xx>H || yy>W) { continue; }
				if (dis[xx][yy] != -1) { continue; }
				if (s[xx][yy] == '#') { continue; }
				dis[xx][yy] = dis[x][y] + 1;
				qx.push(xx);
				qy.push(yy);
			}
		}	
	}

	cout << dis[dh][dw] << endl;
}


Measured memory_bytes: 12632