#include<bits/stdc++.h>
using namespace std;
#define rep(i,n) for(ll i=0;i<n;i++)
#define repl(i,l,r) for(ll i=(l);i<(r);i++)
#define per(i,n) for(ll i=(n)-1;i>=0;i--)
#define perl(i,r,l) for(ll i=r-1;i>=l;i--)
#define fi first
#define se second
#define ins insert
#define pqueue(x) priority_queue<x,vector<x>,greater<x>>
#define all(x) (x).begin(),(x).end()
#define CST(x) cout<<fixed<<setprecision(x)
#define rev(x) reverse(x);
using ll=long long;
using vl=vector<ll>;
using vvl=vector<vector<ll>>;
using pl=pair<ll,ll>;
using vpl=vector<pl>;
using vvpl=vector<vpl>;
const ll MOD=1000000007;
const ll MOD9=998244353;
const int inf=1e9+10;
const ll INF=4e18;
const ll dy[8]={1,0,-1,0,1,1,-1,-1};
const ll dx[8]={0,1,0,-1,1,-1,1,-1};
template <typename T> inline bool chmax(T &a, T b) {
  return ((a < b) ? (a = b, true) : (false));
}
template <typename T> inline bool chmin(T &a, T b) {
  return ((a > b) ? (a = b, true) : (false));
}

int main(){
  ll h,w;cin >> h >> w;
  ll sx,sy,gx,gy;cin >> sx >> sy >> gx >> gy;
  sx--;sy--;gx--;gy--;
  vector<string> g(h);rep(i,h)cin >> g[i];
  queue<ll> que;que.push(sx*w+sy);
  vvl seen(h,vl(w));seen[sx][sy]=1;
  while(que.size()){
    ll x=que.front()/w,y=que.front()%w;que.pop();
    rep(i,4){
      ll nx=x+dx[i],ny=y+dy[i];
      if(nx<0||ny<0||nx>=h||ny>=w)continue;
      if(seen[nx][ny])continue;
      if(abs(g[nx][ny]-g[x][y])<=1){
        que.push(nx*w+ny);
        seen[nx][ny]=1;
      }
      ll nnx=nx+dx[i],nny=ny+dy[i];
      if(nnx<0||nny<0||nnx>=h||nny>=w)continue;
      if(seen[nnx][nny])continue;
      if(g[nnx][nny]==g[x][y]&&g[x][y]-g[nx][ny]>0){
        que.push(nnx*w+nny);
        seen[nnx][nny]=1;
      }
    }
  }
  if(seen[gx][gy])cout << "YES" << endl;
  else cout << "NO" << endl;
}