using System;
using System.Collections;
using System.Collections.Generic;
using System.Diagnostics;
using System.Globalization;
using System.IO;
using System.Text;
using System.Linq;

using E = System.Linq.Enumerable;
using System.Threading;

internal partial class Solver {
    public void Run() {
        var h = ni();
        var w = ni();
        var ch = ni() - 1;
        var cw = ni() - 1;
        var dh = ni() - 1;
        var de = ni() - 1;
        var map = ns(h);
        var deque = new Deque<(int Row, int Col, int Warp)>();
        deque.PushBack((ch, cw, 0));
        var visited = new bool[h, w];
        int ans = -1;
        while (deque.Count > 0) {
            var (row, col, warp) = deque.PopFront();
            if (row == dh && col == de) {
                ans = warp;
                break;
            }
            if (visited[row, col]) continue;
            visited[row, col] = true;
            for (int dr = -2; dr <= 2; dr++) {
                for (int dc = -2; dc <= 2; dc++) {
                    var d = Math.Abs(dr) + Math.Abs(dc);
                    if (d == 0) continue;
                    var nr = row + dr;
                    var nc = col + dc;
                    if ((0 <= nr && nr < h) && (0 <= nc && nc < w) && map[nr][nc] == '.') {
                        if (d == 1) {
                            deque.PushFront((nr, nc, warp));
                        } else {
                            deque.PushBack((nr, nc, warp + 1));
                        }
                    }
                }
            }
        }
        cout.WriteLine(ans);
    }
}

public partial class Deque<T> {
    private T[] _array;
    private int _head;
    private int _tail;
    public int Count { get; private set; }

    public Deque(int capacity = 16) {
        _array = new T[capacity];
        _head = 0;
        _tail = 0;
    }

    public void Clear() {
        _head = _tail = Count = 0;
    }

    public void PushBack(T value) {
        if (Count + 1 == _array.Length) {
            Expand();
        }
        Count++;

        _array[_tail++] = value;
        if (_tail == _array.Length) {
            _tail = 0;
        }
    }

    public void PushFront(T value) {
        if (Count + 1 == _array.Length) {
            Expand();
        }
        Count++;

        if (--_head == -1) {
            _head += _array.Length;
        }
        _array[_head] = value;
    }

    public T PopBack() {
        if (Count == 0) {
            throw new Exception("empty");
        }

        Count--;
        if (--_tail == -1) {
            _tail += _array.Length;
        }
        return _array[_tail];
    }

    public T PeekBack() {
        if (Count == 0) {
            throw new Exception("empty");
        }

        return this[Count - 1];
    }

    public T PopFront() {
        if (Count == 0) {
            throw new Exception("empty");
        }

        var ret = _array[_head];
        Count--;
        if (++_head == _array.Length) {
            _head = 0;
        }
        return ret;
    }

    public T PeekFront() {
        if (Count == 0) {
            throw new Exception("empty");
        }

        return _array[_head];
    }

    public T this[int index] {
        get {
            if (index < 0 || index >= Count) {
                throw new Exception("Invalid index");
            }
            index += _head;
            if (index >= _array.Length) {
                index -= _array.Length;
            }

            return _array[index];
        }
        set {
            if (index < 0 || index >= Count) {
                throw new Exception("Invalid index");
            }
            index += _head;
            if (index >= _array.Length) {
                index -= _array.Length;
            }

            _array[index] = value;
        }
    }

    private void Expand() {
        var newarray = new T[_array.Length * 2];

        if (_head < _tail) {
            Array.Copy(_array, _head, newarray, 0, Count);
        } else {
            Array.Copy(_array, _head, newarray, 0, _array.Length - _head);
            Array.Copy(_array, 0, newarray, _array.Length - _head, _tail);
        }

        _array = newarray;
        _head = 0;
        _tail = Count == newarray.Length ? 0 : Count;
    }

}
// PREWRITEN CODE BEGINS FROM HERE

static public class StringExtensions {
    static public string JoinToString<T>(this IEnumerable<T> source, string separator = " ") {
        return string.Join(separator, source);
    }
}

internal partial class Solver : Scanner {
    static readonly int? StackSizeInMebiByte = null; //50;
    public static void StartAndJoin(Action action, int maxStackSize) {
        var thread = new Thread(new ThreadStart(action), maxStackSize);
        thread.Start();
        thread.Join();
    }

    public static void Main() {
#if LOCAL
        byte[] inputBuffer = new byte[1000000];
        var inputStream = Console.OpenStandardInput(inputBuffer.Length);
        using (var reader = new StreamReader(inputStream, Console.InputEncoding, false, inputBuffer.Length)) {
            Console.SetIn(reader);
            new Solver(Console.In, Console.Out).Run();
        }
#else
        Console.SetOut(new StreamWriter(Console.OpenStandardOutput()) { AutoFlush = false });
        if (StackSizeInMebiByte.HasValue) {
            StartAndJoin(() => new Solver(Console.In, Console.Out).Run(), StackSizeInMebiByte.Value * 1024 * 1024);
        } else {
            new Solver(Console.In, Console.Out).Run();
        }
        Console.Out.Flush();
#endif
    }

#pragma warning disable IDE0052
    private readonly TextReader cin;
    private readonly TextWriter cout;
    private readonly TextWriter cerr;
#pragma warning restore IDE0052

    public Solver(TextReader reader, TextWriter writer)
        : base(reader) {
        cin = reader;
        cout = writer;
        cerr = Console.Error;
    }

    public Solver(string input, TextWriter writer)
        : this(new StringReader(input), writer) {
    }

#pragma warning disable IDE1006
#pragma warning disable IDE0051
    private int ni() { return NextInt(); }
    private int[] ni(int n) { return NextIntArray(n); }
    private long nl() { return NextLong(); }
    private long[] nl(int n) { return NextLongArray(n); }
    private double nd() { return NextDouble(); }
    private double[] nd(int n) { return NextDoubleArray(n); }
    private string ns() { return Next(); }
    private string[] ns(int n) { return NextArray(n); }
#pragma warning restore IDE1006
#pragma warning restore IDE0051
}

#if DEBUG
internal static class LinqPadExtension {
    public static string TextDump<T>(this T obj) {
        if (obj is IEnumerable) return (obj as IEnumerable).Cast<object>().JoinToString().Dump();
        else return obj.ToString().Dump();
    }
    public static T Dump<T>(this T obj) {
        return LINQPad.Extensions.Dump(obj);
    }
}
#endif

public class Scanner {
    private readonly TextReader Reader;
    private readonly CultureInfo ci = CultureInfo.InvariantCulture;

    private readonly char[] buffer = new char[2 * 1024];
    private int cursor = 0, length = 0;
    private string Token;
    private readonly StringBuilder sb = new StringBuilder(1024);

    public Scanner()
        : this(Console.In) {
    }

    public Scanner(TextReader reader) {
        Reader = reader;
    }

    public int NextInt() { return checked((int)NextLong()); }
    public long NextLong() {
        var s = Next();
        long r = 0;
        int i = 0;
        bool negative = false;
        if (s[i] == '-') {
            negative = true;
            i++;
        }
        for (; i < s.Length; i++) {
            r = r * 10 + (s[i] - '0');
#if DEBUG
            if (!char.IsDigit(s[i])) throw new FormatException();
#endif
        }
        return negative ? -r : r;
    }
    public double NextDouble() { return double.Parse(Next(), ci); }
    public string[] NextArray(int size) {
        string[] array = new string[size];
        for (int i = 0; i < size; i++) {
            array[i] = Next();
        }

        return array;
    }
    public int[] NextIntArray(int size) {
        int[] array = new int[size];
        for (int i = 0; i < size; i++) {
            array[i] = NextInt();
        }

        return array;
    }

    public long[] NextLongArray(int size) {
        long[] array = new long[size];
        for (int i = 0; i < size; i++) {
            array[i] = NextLong();
        }

        return array;
    }

    public double[] NextDoubleArray(int size) {
        double[] array = new double[size];
        for (int i = 0; i < size; i++) {
            array[i] = NextDouble();
        }

        return array;
    }

    public string Next() {
        if (Token == null) {
            if (!StockToken()) {
                throw new Exception();
            }
        }
        var token = Token;
        Token = null;
        return token;
    }

    public bool HasNext() {
        if (Token != null) {
            return true;
        }

        return StockToken();
    }

    private bool StockToken() {
        while (true) {
            sb.Clear();
            while (true) {
                if (cursor >= length) {
                    cursor = 0;
                    if ((length = Reader.Read(buffer, 0, buffer.Length)) <= 0) {
                        break;
                    }
                }
                var c = buffer[cursor++];
                if (33 <= c && c <= 126) {
                    sb.Append(c);
                } else {
                    if (sb.Length > 0) break;
                }
            }

            if (sb.Length > 0) {
                Token = sb.ToString();
                return true;
            }

            return false;
        }
    }
}

Measured memory_bytes: 32740