#include<iostream>
using namespace std;
int h,w;
bool can[51][51];
string b[51];
void search(int x,int y){
  int dx[]={1,0,-1,0},dy[]={0,1,0,-1},nx,ny,nnx,nny;
  if(can[x][y])return;
  can[x][y]=true;
  for(int i=0;i<4;i++){
    nx=x+dx[i];
    ny=y+dy[i];
    if(nx<0||nx>=h||ny<0||ny>=w) continue;
    if(abs(b[x][y]-b[nx][ny])<=1) search(nx,ny);

    nnx=x+2*dx[i];
    nny=y+2*dy[i];
    if(nnx<0||nnx>=h||nny<0||nny>=w) continue;
    if(b[x][y]==b[nnx][nny]){
      if(b[x][y]-b[nx][ny]>=0) search(nnx,nny);
    }
  }
}
int main(){
  int sx,sy,gx,gy;
  cin >> h >> w>>sx>>sy>>gx>>gy;
  for(int i=0;i<h;i++){
    cin >> b[i];
    fill(can[i],can[i]+w,false);
  }
  sx--;sy--;gx--;gy--;
  search(sx,sy);
  if(can[gx][gy])cout <<"YES\n";
  else cout <<"NO\n";
}