#include<iostream>
#include<cstdio>
#include<vector>
#include<map>
#include<tuple>
#include<string>
#include<sstream>
#include<cmath>
#include<climits>
#include<algorithm>
#include<bitset>
#include<set>
#include<stack>
#include<queue>
#include<iomanip>
#include<memory.h>
using namespace std;  
typedef long long ll;
typedef vector<int> vi;
typedef vector<vi> vvi;
#define rep(i,n) for(ll i=0;i<(n);i++)  
#define tii tuple<int,int>
#define tiii tuple<int,int,int>
#define mt make_tuple
#define pb push_back  
#define ALL(a) (a).begin(),(a).end()
#define FST first
#define SEC second  
const int INF = (INT_MAX/2);
const ll LLINF = (LLONG_MAX/2);
const double eps = 1e-5;
const double PI = M_PI;  
#define DEB cerr<<"!"<<endl
#define SHOW(a,b) cerr<<(a)<<" "<<(b)<<endl
#define SHOWARRAY(ar,i,j) REP(a,i)REP(b,j)cerr<<ar[a][b]<<((b==j-1)?((a==i-1)?("\n\n"):("\n")):(" "))
#define DIV int(1e9+7)
inline ll pow(ll x,ll n,ll m){ll r=1;while(n>0){if((n&1)==1)r=r*x%m;x=x*x%m;n>>=1;}return r%m;}


bool used[50][50] = {};
vi vec1 ={0,-1,0,1,0};
vi vec2 ={0,2,0,-2,0};

int main(){
  int h,w,sx,sy,gx,gy; cin >> h >> w >> sx >> sy >> gx >> gy;
  sx--,sy--,gx--,gy--;
  vector<string> vs;
  rep(i,h){string sin; cin >> sin; vs.pb(sin);}
  stack<tii> s;
  s.push(tii{sx,sy});
  while(!s.empty()){ 
    int x,y; tie(x,y) = s.top(); s.pop();
    //SHOW(x,y);  
    //SHOW(vs[x][y],0);
    used[x][y] = 1;
    if(gx == x && gy == y){cout <<"YES" << endl; return 0;}
    rep(i,4){
      int nx = vec1[i] + x;
      int ny = vec1[i+1] + y;
      if(used[nx][ny] == 0 && nx >= 0 && nx < h && ny >= 0&& ny < w && abs(vs[nx][ny]-vs[x][y]) <= 1)
        s.push(tii{nx,ny});
    }
    rep(i,4){
      int nx = vec2[i] + x;
      int ny = vec2[i+1] + y;
      if(used[nx][ny] == 0 && nx >= 0 && nx < h && ny >= 0&& ny < w && abs(vs[nx][ny]-vs[x][y]) <= 0)
        s.push(tii{nx,ny});
    }
  }
  cout << "NO" << endl;
  return 0;
}