using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Net;
using static System.Console;
using static System.Math;
using static CS_Contest.Utils;
using System.Numerics;
using System.Linq.Expressions;
using Nakov.IO;
//using static CS_Contest.Library;
namespace CS_Contest {
using Li = List<int>;
using LLi = List<List<int>>;
using Ll = List<long>;
internal class Program {
private static void Main(string[] args) {
var sw = new StreamWriter(OpenStandardOutput()) { AutoFlush = false };
SetOut(sw);
new Calc().Solve();
Out.Flush();
}
public class Calc {
public void Solve() {
List<List<char>> list = new List<List<char>>();
int R = Cin.NextInt();
int C = Cin.NextInt();
int sy = Cin.NextInt(), sx = Cin.NextInt();
int gy = Cin.NextInt(), gx = Cin.NextInt();
sy--;sx--;gy--; gx--;
REP(R, _ => list.Add(ReadLine().ToList()));
var Q = new Queue<Tuple<int, int,int>>();
Q.Enqueue(new Tuple<int, int,int>(sx, sy,0));
var dx = new [] { -1, 0, 1, 0 };
var dy = new[] { 0, -1, 0, 1 };
//int step = 0;
while (Q.Any()) {
var item = Q.Dequeue();
if (item.Item1 == gx && item.Item2 == gy) { (item.Item3).WL();return; }
for (int i = 0; i < 4; i++) {
var x = dx[i] + item.Item1;
var y = dy[i] + item.Item2;
if (x < 0 || y >= R || x >= C || y < 0 || list[y][x] == '#'||list[y][x]=='_') continue;
list[y][x] = '_';
Q.Enqueue(new Tuple<int, int,int>(x, y,item.Item3+1));
}
}
}
}
}
public static class Utils {
public static long ModValue = (long)1e9 + 7;
public static long INF = long.MaxValue;
public static long Mod(long x) => x % ModValue;
public static long ModPow(long x, long n) {
long tmp = 1; while (n != 0) { if (n % 2 == 1) { tmp = Mod(tmp * x); } x = Mod(x * x); n /= 2; }
return tmp;
}
public static long DivMod(long x, long y) => Mod(x * ModPow(y, (long)(1e9 + 5)));
public static void WL(this object obj) => WriteLine(obj);
public static void WL(this string obj) => WriteLine(obj);
public static void WL<T>(this IEnumerable<T> list) => list.ToList().ForEach(x => x.WL());
public static Li ReadInt() => ReadLine().Split().Select(int.Parse).ToList();
public static string StringJoin<T>(this IEnumerable<T> l, string separator = "") => string.Join(separator, l);
public static long GCD(long m, long n) {
long tmp;
if (m < n) { tmp = n; n = m; m = tmp; }
while (m % n != 0) {
tmp = n;
n = m % n;
m = tmp;
}
return n;
}
public static long LCM(long m, long n) => m * (n / GCD(m, n));
public static void REP(int n, Action<int> act) {
for (var i = 0; i < n; i++) {
act(i);
}
}
public static int ManhattanDistance(int x1, int y1, int x2, int y2) => Abs(x2 - x1) + Abs(y2 - y1);
public struct IndexT<T> {
public T Value { get; set; }
public int Index { get; set; }
public IndexT(T v, int i) {
Value = v; Index = i;
}
public override string ToString() {
return Value + " " + Index;
}
}
public static IEnumerable<IndexT<T>> ToIndexEnumerable<T>(this IEnumerable<T> list) => list.Select((x, i) => new IndexT<T>(x, i));
public static Queue<T> ToQueue<T>(this IEnumerable<T> iEnumerable) {
var rt = new Queue<T>();
foreach (var item in iEnumerable) {
rt.Enqueue(item);
}
return rt;
}
public static IndexT<T> IndexOf<T>(this IEnumerable<T> ie, Func<IndexT<T>, IndexT<T>, IndexT<T>> func) =>
ie.ToIndexEnumerable().Aggregate(func);
public static T[] Range<T>(int range,Func<int,T> func) {
var rt = new T[range];
for (var i = 0; i < range; i++) rt[i] = func(i);
return rt;
}
public static void Swap<T>(ref T x,ref T y) {
var tmp = x;
x = y;
y = tmp;
}
public static Dictionary<TKey,int> CountUp<TKey>(this IEnumerable<TKey> l) {
var dic = new Dictionary<TKey, int>();
foreach (var item in l) {
if (dic.ContainsKey(item)) dic[item]++;
else dic.Add(item, 1);
}
return dic;
}
public static int Count<T>(this IEnumerable<T> l, T target) => l.Count(x => x.Equals(target));
}
}
namespace Nakov.IO {
using System;
using System.Text;
using System.Globalization;
public static class Cin {
public static string NextToken() {
StringBuilder tokenChars = new StringBuilder();
bool tokenFinished = false;
bool skipWhiteSpaceMode = true;
while (!tokenFinished) {
int nextChar = Console.Read();
if (nextChar == -1) {
tokenFinished = true;
} else {
char ch = (char)nextChar;
if (char.IsWhiteSpace(ch)) {
if (!skipWhiteSpaceMode) {
tokenFinished = true;
if (ch == '\r' && (Environment.NewLine == "\r\n")) {
Console.Read();
}
}
} else {
skipWhiteSpaceMode = false;
tokenChars.Append(ch);
}
}
}
string token = tokenChars.ToString();
return token;
}
public static int NextInt() {
string token = Cin.NextToken();
return int.Parse(token);
}
public static double NextDouble(bool acceptAnyDecimalSeparator = true) {
string token = Cin.NextToken();
if (acceptAnyDecimalSeparator) {
token = token.Replace(',', '.');
double result = double.Parse(token, CultureInfo.InvariantCulture);
return result;
} else {
double result = double.Parse(token);
return result;
}
}
public static decimal NextDecimal(bool acceptAnyDecimalSeparator = true) {
string token = Cin.NextToken();
if (acceptAnyDecimalSeparator) {
token = token.Replace(',', '.');
decimal result = decimal.Parse(token, CultureInfo.InvariantCulture);
return result;
} else {
decimal result = decimal.Parse(token);
return result;
}
}
}
}