#include <iostream>
#include <cstdio>
#include <cmath>
#include <ctime>
#include <cstdlib>
#include <cassert>
#include <vector>
#include <list>
#include <stack>
#include <queue>
#include <deque>
#include <map>
#include <set>
#include <bitset>
#include <string>
#include <algorithm>
#include <utility>
#define llint long long
#define inf 1e18
#define rep(x, s, t) for(llint (x) = (s); (x) < (t); (x)++)
#define Rep(x, s, t) for(llint (x) = (s); (x) <= (t); (x)++)
#define chmin(x, y) (x) = min((x), (y))
#define chmax(x, y) (x) = max((x), (y))

using namespace std;
typedef pair<llint, llint> P;

llint h, w;
llint sx, sy, gx, gy;
char c[1005][1005];
llint dist[1005][1005];
int dx[] = {1, 0, -1, 0}, dy[] = {0, -1, 0, 1};

void bfs()
{
	queue<P> Q;
	Q.push(P(sx, sy));
	
	for(int y = 1; y <= h; y++){
		for(int x = 1; x <= w; x++){
			dist[x][y] = inf;
		}
	}
	dist[sx][sy] = 0;
	
	llint x, y;
	while(Q.size()){
		x = Q.front().first, y = Q.front().second;
		Q.pop();
		for(int i = 0; i < 4; i++){
			llint nx = x + dx[i], ny = y + dy[i];
			if(nx < 1 || nx > w || ny < 1 || ny > h) continue;
			//if(c[nx][ny] == '#') continue;
			if(dist[nx][ny] < inf/2) continue;
			dist[nx][ny] = dist[x][y] + 1;
			Q.push(P(nx, ny));
		}
	}
}

int main(void)
{
	ios::sync_with_stdio(0);
	cin.tie(0);
	
	cin >> h >> w;
	cin >> sy >> sx >> gy >> gx;
	for(int y = 1; y <= h; y++){
		for(int x = 1; x <= w; x++){
			cin >> c[x][y];
		}
	}
	
	bfs();
	
	cout << dist[gx][gy] << endl;
	
	return 0;
}