#include <bits/stdc++.h>
#define rep(i,a,b) for(int i=(a);i<=(b);++i)
#define per(i,a,b) for(int i=(a);i>=(b);--i)
#define pii pair<int,int>
#define fi first
#define se second
#define pb push_back
#define ll long long
using namespace std;
inline ll read(){
    ll x=0,f=1;char ch=getchar();
    while (!isdigit(ch)){if (ch=='-') f=-1;ch=getchar();}
    while (isdigit(ch)){x=x*10+ch-48;ch=getchar();}
    return x*f;
}
const int N=1007,d[4][2]={{1,0},{0,1},{-1,0},{0,-1}},inf=1e9;
int n,m,r1,c1,r2,c2,dis[N][N];
int A[N][N],W[N][N],S[N][N],D[N][N];
bool vis[N][N];
char Map[N][N];
queue <pii> q;
void upd(int x,int y,int d){
    if(Map[x][y]=='.'&&d<dis[x][y]){
        dis[x][y]=d;
        if(!vis[x][y]){
            vis[x][y]=1;
            q.push({x,y});
        }
    }
}
void bfs(){
    dis[r1][c1]=0,vis[r1][c1]=1;
    q.push({r1,c1});
    while(!q.empty()){
        int x=q.front().fi,y=q.front().se;
        int Dis=dis[x][y];
        q.pop();
        //反复横跳
        rep(i,0,3){
            int nx=x+d[i][0],ny=y+d[i][1];
            upd(nx,ny,Dis+2);
        }
        //直接走
        upd(x,A[x][y]+1,Dis+1);upd(x,D[x][y]-1,Dis+1);
        upd(W[x][y]+1,y,Dis+1);upd(S[x][y]-1,y,Dis+1);
        vis[x][y]=0;
    }
}
int main(){
    n=read(),m=read();
    rep(i,1,n){
        scanf("%s",Map[i]+1);
        rep(j,1,m)dis[i][j]=inf;
    }
    rep(i,1,n){
        rep(j,1,m){
            if(Map[i][j]=='#')A[i][j]=j;
            else A[i][j]=A[i][j-1];
        }
        per(j,m,1){
            if(Map[i][j]=='#')D[i][j]=j;
            else D[i][j]=D[i][j+1];
        }
    }
    rep(j,1,m){
        rep(i,1,n){
            if(Map[i][j]=='#')W[i][j]=i;
            else W[i][j]=W[i-1][j];
        }
        per(i,n,1){
            if(Map[i][j]=='#')S[i][j]=i;
            else S[i][j]=S[i+1][j];
        }
    }
    r1=read(),c1=read(),r2=read(),c2=read();
    bfs();
    printf("%d\n",dis[r2][c2]==inf?-1:dis[r2][c2]);
    return 0;
}