#include <bits/stdc++.h>
using namespace std;
#define lli long long int
#define uli unsigned long long int
#define INF 99999999999
#define rep(i,m,n) for(lli i = m;i < n;i++)
#define rrep(i,m,n) for(lli i=m-1;i>=n;i--)
#define pb(n) push_back(n)
#define UE(N) N.erase(unique(N.begin(),N.end()),N.end());
#define Sort(n) sort(n.begin(), n.end())
#define Rev(n) reverse(n.begin(),n.end())
#define Out(S) cout << S << endl
#define NeOut(S) cout << S
#define HpOut(S) cout << setprecision(20) << S << endl
#define Vecpr(K,L1,L2,N) vector<pair<L1,L2>> K(N)
#define Vec(K,L,N,S) vector<L> K(N,S)
#define DV(K,L,N,M,R) vector<vector<L>> K(N, vector<L>(M,R))
#define pint pair<int,int>
#define Lower(v,X) lower_bound(v.begin(),v.end(),X)-v.begin();
#define mod 1000000007
#define MAX 5100000
#define chmax(a, b) a = (((a)<(b)) ? (b) : (a))
#define chmin(a, b) a = (((a)>(b)) ? (b) : (a))
int dx[4] = {1, 0, -1, 0};
int dy[4] = {0, 1, 0, -1};
int main(){
   lli A,B,C,L,R,N,M,K,X=0,Y=0,W,H=INF,sum=0,num=0,flag=0;string S,T,O;
   cin >> W >> H >> A >> B >> L >> R;
   DV(P,char,W,H,'.');
   rep(i,0,W)rep(j,0,H)cin >> P[i][j];
   DV(dist,int,W,H,-1);
   dist[A-1][B-1]=0;
   queue<pint> que;
   que.push(pint(A-1,B-1));
   while(!que.empty()){
      auto Xq=que.front();que.pop();
      rep(i,0,4){
         lli nx=Xq.first+dx[i];
         lli ny=Xq.second+dy[i];
         if(P[nx][ny]=='#'||dist[nx][ny]!=-1)continue;
         dist[nx][ny]=dist[Xq.first][Xq.second]+1;
         que.push(pint(nx,ny));
      }
   }
   Out(dist[L-1][R-1]);
}