#include <bits/stdc++.h>
#define REP(i,n,N) for(int i=(n);i<(int) N;i++)
#define p(s) cout<<(s)<<endl
#define CK(n,a,b) ((a)<=(n)&&(n)<(b))
#define F first
#define S second
using namespace std;

bool ok[55][55];
string field[55];
int dx[]={1,0,-1,0};
int dy[]={0,1,0,-1};
int main() {
	int h,w;
	int sx,sy,gx,gy;
	cin>>h>>w>>sx>>sy>>gx>>gy;
	REP(i,0,h) cin>>field[i];
	sy--;sx--;gy--;gx--;
	ok[sx][sy]=true;
	queue<pair<int,int>> q;
	q.push({sx,sy});
	while(!q.empty()){
		auto now=q.front();q.pop();
		REP(i,0,4){
			int nx=now.F+dx[i],ny=now.S+dy[i];
			if(!ok[nx][ny]&&CK(nx,0,h)&&CK(ny,0,w)&&abs(field[now.F][now.S]-field[nx][ny])<=1){
				ok[nx][ny]=true;
				q.push({nx,ny});
			}
			ny+=dy[i];nx+=dx[i];
			if(!ok[nx][ny]&&CK(nx,0,h)&&CK(ny,0,w)&&field[nx][ny]==field[now.F][now.S]){
				ok[nx][ny]=true;
				q.push({nx,ny});
			}
		}
	}
	p(ok[gx][gy]?"YES":"NO");
	return 0;
}