#include <bits/stdc++.h>
using namespace std;

int main()
{
vector<int> mx={0,1,0,-1};vector<int> my={1,0,-1,0};
int R,C,sy,sx,gy,gx,y,x,Y,X;scanf("%d %d %d %d %d %d",&R,&C,&sy,&sx,&gy,&gx);
vector<vector<char>> c(R,vector<char>(C));vector<vector<int>> dist(R,vector<int>(C,-1));
for(int i=0;i<R;i++)for(int j=0;j<C;j++)cin>>c[i][j];
queue<int> que;que.push(sy-1);que.push(sx-1);dist[sy-1][sx-1]=0;
while(!que.empty())
{
  y=que.front();que.pop();x=que.front();que.pop();
  for(int i=0;i<4;i++)
 {
    Y=y+my[i];X=x+mx[i];
    if(c[Y][X]!='.'||dist[Y][X]!=-1)continue;
    dist[Y][X]=dist[y][x]+1;
    que.push(Y);que.push(X);
    if(Y==gy-1&&X==gx-1){printf("%d\n",dist[gy-1][gx-1]);return 0;}
  }
}
}