#include <iostream>
#include <string>
#include <algorithm>
#include <vector>
#include <iomanip>
#include <cmath>
#include <stdio.h>
#include <queue>
#include <deque>
#include <cstdio>
#include <set>
#include <map>
#include <bitset>
#include <stack>
#include <cctype>
using namespace std;
int main(){
	int r, c;
	int s1, s2, g1, g2;
	char m[51][51];
	queue<int> bfs;
	queue<int> bfs1;
	int bfs2[50][50] = { 0 };
	int ans = 0;
	int b1[4] = { 0,0,1,-1 };
	int b2[4] = { 1,-1,0,0 };
	cin >> r >> c >> s1 >> s2 >> g1 >> g2;
	s1--;
	s2--;
	g1--;
	g2--;
	bfs.push(s2);
	bfs1.push(s1);
	for (int a = 0; a < r; a++) {
		for (int b = 0; b < c; b++) {
			cin >> m[b][a];
		}
	}
	for (;;) {
		for (int i = 0; i < 4; i++) {
			if (m[bfs.front() + b1[i]][bfs1.front() + b2[i]] == '.' && bfs2[bfs.front() + b1[i]][bfs1.front() + b2[i]] == 0) {
				bfs.push(bfs.front() + b1[i]);
				bfs1.push(bfs1.front() + b2[i]);
				bfs2[bfs.front() + b1[i]][bfs1.front() + b2[i]] = bfs2[bfs.front()][bfs1.front()] + 1;
			}
		}
		ans++;
		bfs.pop();
		bfs1.pop();
		if (bfs.front() == g2 && bfs1.front() == g1) {
			cout << bfs2[bfs.front()][bfs1.front()] << endl;
			return 0;
		}
	}
}