#include <iostream>
#include <string>
#include <utility>
#include <algorithm>
#include <map>
#include <set>
#include <vector>
#include <cmath>
#include <cstdlib>
#include <queue>
#include <stack>
#include <iomanip>
#include <fstream>
#include <unordered_map>
#include <unordered_set>
using namespace std;


#define REP(i, n) for(ll i = 0;i < n;i++)
#define REPR(i, n) for(ll i = n;i >= 0;i--)
#define FOR(i, m, n) for(ll i = m;i < n;i++)
#define FORR(i, m, n) for(ll i = m;i >= n;i--)
#define REPO(i, n) for(ll i = 1;i <= n;i++)
#define ll long long
#define INF (ll)1 << 60
#define MINF (-1 * INF)
#define ALL(n) n.begin(),n.end()
#define MOD 1000000007
#define P pair<ll, ll>

vector<vector<ll>> d(1100, vector<ll>(1100, INF));
ll v1[4] = { 0,0,1,-1 }, v2[4] = { 1,-1,0,0 };
int main() {
	ll h, w;
	cin >> h >> w;
	ll h1, w1, h2, w2;
	cin >> h1 >> w1 >> h2 >> w2;
	string s[1100];
	REP(i, w + 2) s[0].push_back('.');
	REP(i, h) {
		s[i + 1].push_back('.');
		REP(j, w) {
			char a;
			cin >> a;
			s[i + 1].push_back(a);
		}
		s[i + 1].push_back('.');
	}
	REP(i, w + 2) s[h + 1].push_back('.');
	h += 2;
	w += 2;
	queue<P> q;
	q.push(P(h1, w1));
	d[h1][w1] = 0;
	while (!q.empty()) {
		P v = q.front();
		q.pop();
		if (v == P(h2, w2)) {
			cout << d[h2][w2] << endl;
			return 0;
		}
		REP(l, 4) {
			ll x = v.first + v1[l], y = v.second + v2[l];
			if (0 > x or x >= h or 0 > y or y >= w)continue;
			if (d[v.first][v.second] + 1 < d[x][y]) {
				d[x][y] = d[v.first][v.second] + 1;
				q.push(P(x, y));
			}
		}
	}
}