W,H=gets.split.map &:to_i
Sx,Sy,Gx,Gy=gets.split.map &:to_i
T=W.times.map{gets.chop.chars.map &:to_i}
ag=[[Sx-1,Sy-1]]

$><<(H*W).times{|o|
  break(:YES)if ag&[[Gx-1,Gy-1]]!=[]
  break(:NO)if !(b=ag[o])
  h=T[b[0]][b[1]]
  [[-1,0],[1,0],[0,-1],[0,1]].each{|i,j|
    k,l=b[0]+i,b[1]+j
    m,n=k+i,l+j
    t=h-T[k][l] rescue 0
    ag<<[k,l]if k>=0&&k<W&&l>=0&&l<H&&ag&[[k,l]]==[]&&t.abs<2
    ag<<[m,n]if m>=0&&m<W&&n>=0&&n<H&&ag&[[m,n]]==[]&&h==T[m][n]&&t>0
  }
}