import java.io.BufferedWriter;
import java.io.FileInputStream;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.ArrayDeque;
import java.util.BitSet;
import java.util.HashMap;
import java.util.Queue;
public class Main {
public static void main(String[] args) throws NumberFormatException,
IOException {Solve solve = new Solve();solve.solve();}
}
class Solve{
void dump(int[]a){for(int i=0;i<a.length;i++)System.out.print(a[i]+" ");System.out.println();}
void dump(int[]a,int n){for(int i=0;i<a.length;i++)System.out.printf("%"+n+"d",a[i]);System.out.println();}
void dump(long[]a){for(int i=0;i<a.length;i++)System.out.print(a[i]+" ");System.out.println();}
void dump(char[]a){for(int i=0;i<a.length;i++)System.out.print(a[i]);System.out.println();}
long pow(long a,int n){long r=1;while(n>0){if((n&1)==1)r*=a;a*=a;n>>=1;}return r;}
String itob(int a,int l){return String.format("%"+l+"s",Integer.toBinaryString(a)).replace(' ','0');}
void solve() throws NumberFormatException, IOException{
final ContestScanner in = new ContestScanner();
Writer out = new Writer();
int r = in.nextInt();
int c = in.nextInt();
int sy = in.nextInt()-1;
int sx = in.nextInt()-1;
int gy = in.nextInt()-1;
int gx = in.nextInt()-1;
char[][] map = new char[r][];
for(int i=0; i<r; i++) map[i] = in.nextToken().toCharArray();
Queue<Pos> qu = new ArrayDeque<>();
qu.add(new Pos(sy, sx, 0));
BitSet used = new BitSet(r*c);
final int[] dy = {1, -1, 0, 0};
final int[] dx = {0, 0, 1, -1};
while(!qu.isEmpty()){
Pos p = qu.poll();
if(used.get(p.y*c+p.x)) continue;
used.set(p.y*c+p.x);
final int d = p.d;
final int y = p.y;
final int x = p.x;
if(y==gy && x==gx){
System.out.println(d);
break;
}
for(int i=0; i<4; i++){
final int ny = y+dy[i];
final int nx = x+dx[i];
if(ny<0 || ny>=r || nx<0 || nx>=c || map[ny][nx]=='#')
continue;
qu.add(new Pos(ny, nx, d+1));
}
}
}
}
class Pos{
int d, x, y;
Pos(int y, int x, int d){
this.y = y;
this.x = x;
this.d = d;
}
}
class MultiSet<T> extends HashMap<T, Integer>{
@Override
public Integer get(Object key){return containsKey(key)?super.get(key):0;}
public void add(T key,int v){put(key,get(key)+v);}
public void add(T key){put(key,get(key)+1);}
public void sub(T key)
{final int v=get(key);if(v==1)remove(key);else put(key,v-1);}
}
class Timer{
long time;
public void set(){time=System.currentTimeMillis();}
public long stop(){return time=System.currentTimeMillis()-time;}
public void print()
{System.out.println("Time: "+(System.currentTimeMillis()-time)+"ms");}
@Override public String toString(){return"Time: "+time+"ms";}
}
class Writer extends PrintWriter{
public Writer(String filename)throws IOException
{super(new BufferedWriter(new FileWriter(filename)));}
public Writer()throws IOException{super(System.out);}
}
class ContestScanner {
private InputStreamReader in;private int c=-2;
public ContestScanner()throws IOException
{in=new InputStreamReader(System.in);}
public ContestScanner(String filename)throws IOException
{in=new InputStreamReader(new FileInputStream(filename));}
public String nextToken()throws IOException {
StringBuilder sb=new StringBuilder();
while((c=in.read())!=-1&&Character.isWhitespace(c));
while(c!=-1&&!Character.isWhitespace(c)){sb.append((char)c);c=in.read();}
return sb.toString();
}
public String readLine()throws IOException{
StringBuilder sb=new StringBuilder();if(c==-2)c=in.read();
while(c!=-1&&c!='\n'&&c!='\r'){sb.append((char)c);c=in.read();}
return sb.toString();
}
public long nextLong()throws IOException,NumberFormatException
{return Long.parseLong(nextToken());}
public int nextInt()throws NumberFormatException,IOException
{return(int)nextLong();}
public double nextDouble()throws NumberFormatException,IOException
{return Double.parseDouble(nextToken());}
}