#include<iostream>
#include<vector>
#include<string>
#include<algorithm>	
#include<map>
#include<set>
#include<utility>
#include<cmath>
#include<cstring>
#include<queue>
#include<stack>
#include<cstdio>
#include<sstream>
#include<iomanip>
#include<assert.h>
#define loop(i,a,b) for(int i=a;i<b;i++) 
#define rep(i,a) loop(i,0,a)
#define pb push_back
#define mt make_tuple
#define all(in) in.begin(),in.end()
#define shosu(x) fixed<<setprecision(x)
using namespace std;
//kaewasuretyuui
typedef long long ll;
typedef pair<int,int> pii;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<pii> vp;
typedef vector<vp> vvp;
typedef vector<string> vs;
typedef vector<double> vd;
typedef tuple<int,int,int> tp;
typedef vector<tp> vt;
typedef vector<vd> vvd;
typedef pair<int,pii> pip;
typedef vector<pip>vip;
const double PI=acos(-1);
const double EPS=1e-7;
const int inf=1e9;
const ll INF=1e16;
int dx[]={0,1,0,-1,0,2,0,-2};
int dy[]={1,0,-1,0,2,0,-2,0};
int main(){
	int n,m;
	cin>>n>>m;
	int a,b,c,d;
	cin>>a>>b>>c>>d;
	a--;b--;c--;d--;
	vs in(n);
	rep(i,n)cin>>in[i];
	queue<pii>que;
	vvi dp(n,vi(m));
	dp[a][b]=1;
	que.push(pii(a,b));
	while(!que.empty()){
		pii now=que.front();
		que.pop();
		rep(i,8){
			int nx=now.first+dx[i];
			int ny=now.second+dy[i];
			if(nx<0||ny<0||nx>=n||ny>=m||dp[nx][ny])continue;
			bool h=true;
			if(i<4&&abs(in[now.first][now.second]-in[nx][ny])>1)h=false;
			if(i>=4&&(abs(in[now.first][now.second]-in[nx][ny])>0||in[nx][ny]<in[now.first+dx[i-4]][now.second+dy[i-4]]))h=false;
			if(!h)continue;
			dp[nx][ny]=1;
			que.push(pii(nx,ny));
		}
	}
	if(dp[c][d])cout<<"YES"<<endl;
	else cout<<"NO"<<endl;
}