//Don't have to see. start------------------------------------------
var read = require('readline').createInterface({
  input: process.stdin, output: process.stdout
});
var obj; var inLine = [];
read.on('line', function(input){inLine.push(input);});
read.on('close', function(){
  obj = init(inLine);
  console.error('\n↑入力 ↓出力');
  Main();
});
function makeClone(obj){return (obj instanceof Set) ? new Set(Array.from(obj)) : JSON.parse(JSON.stringify(obj));}
function nextInt(){return myconv(next(),1);} function nextStrArray(){return myconv(next(),2);}
function nextIntArray(){return myconv(next(),4);} function nextCharArray(){return myconv(next(),6);}
function next(){return obj.next();} function hasNext(){return obj.hasNext();}
function init(input){  
  return {
    list : input, index : 0, max : input.length,
    hasNext : function(){return (this.index < this.max);},
    next : function(){if(this.hasNext()){return this.list[this.index++];}else{throw 'ArrayIndexOutOfBoundsException ‚There is no more input';}}
  };
}
function myout(s){console.log(s);}
function myerr(s){console.error('debug:' + require('util').inspect(s,false,null));}
//param "no" is
//unknown or outlier : return i. 1: parseInt.
//2: split space. 4: split space and parseInt.
//6: split 1 character. 7: split 1 character and parseInt.
//8: join space. 9: join nextline. 0: join no character.
function myconv(i,no){try{switch(no){case 1:return parseInt(i);case 2:return i.split(' ');case 4:return i.split(' ').map(Number);case 6:return i.split('');case 7:return i.split('').map(Number);case 8:return i.join(' ');case 9:return i.join('\n');case 0:return i.join('');default:return i;}}catch(e){return i;}}

//Don't have to see. end------------------------------------------
function Main(){
  var one = nextIntArray();
  var H = one[0];
  var W = one[1];
  var two = nextIntArray();
  var sy = two[0] - 1;
  var sx = two[1] - 1;
  var ey = two[2] - 1;
  var ex = two[3] - 1;
  var list = new Array(H);
  for(var i = 0; i < H; i++){
    var tmp = nextCharArray();
    list[i] = new Array(W);
    for(var j = 0; j < W; j++){
      list[i][j] = {
        s : myconv(tmp[j], 1),
        access : false
      }
    }
  }
  var dy = [-1,0,1,0];
  var dx = [0,-1,0,1];
  var dy2 = [-2,0,2,0];
  var dx2 = [0,-2,0,2];
  var queue = [[sy, sx]];
  while(queue.length > 0){
    var now = queue.shift();
    var nowY = now[0];
    var nowX = now[1];
    if(nowY == ey && nowX == ex){
      myout("YES");
      return;
    }
    for(var i = 0; i < dy.length; i++){
      var nextY = nowY + dy[i];
      var nextX = nowX + dx[i];
      try{
        if(Math.abs(list[nowY][nowX].s - list[nextY][nextX].s) <= 1 && !list[nextY][nextX].access){
          list[nextY][nextX].access = true;
          queue.push([nextY, nextX]);
        }
      }catch(e){}
    }
    for(var i = 0; i < dy.length; i++){
      var nextY = nowY + dy2[i];
      var nextX = nowX + dx2[i];
      var aidaY = nowY + dy[i];
      var aidaX = nowX + dx[i];
      try{
        if(list[nowY][nowX].s > list[aidaY][aidaX].s && list[nowY][nowX].s == list[nextY][nextX].s && !list[nextY][nextX].access){
          list[nextY][nextX].access = true;
          queue.push([nextY, nextX]);
        }
      }catch(e){}
    }
  }
  myout("NO");
}