简单题，ACGO

话不多说，正文开始!

#include<bits/stdc++.h>
using namespace std;
int n,m,sx,sy,fx,fy;
char mp[42][42];
int dx[]={-1,0,1,0};
int dy[]={0,1,0,-1};
int vis[42][42];
bool flag=false;
void dfs(int x,int y){
	if(flag||(x==fx&&y==fy)){
		flag=true;
		return;
	}
	vis[x][y]=1;
	for(int i=0;i<4;i++){
		int nx=x+dx[i];
		int ny=y+dy[i];
		if(nx>=1&&nx<=n&&ny>=1&&ny<=m&&vis[nx][ny]==0&&mp[nx][ny]=='.'){
			dfs(nx,ny);
		}
	}
}
int main(){
	cin>>n>>m;
	cin>>sx>>sy>>fx>>fy;
	for(int i=1;i<=n;i++){
		for(int j=1;j<=m;j++){
			cin>>mp[i][j];
		}
	}
	dfs(sx,sy);
	if(flag==true){
		cout<<"YES";
	}else{
		cout<<"NO";
	}
	return 0;
}