W,H=gets.split.map &:to_i
Sx,Sy,Gx,Gy=gets.split.map{|i|i.to_i-1}
T=H.times.map{gets.chomp.chars.map &:to_i}

ag=[[Sx,Sy]]

def candidate(x,y,ag)
  h=T[x][y]
  [[-1,0],[1,0],[0,-1],[0,1]].each{|i,j|
    k,l=x+i,y+j
    t=h-T[k][l]
    ag<<[[k,l]]if k>0&&k<W&&l>0&&l<H&&ag&[k,l]==[]&&t.abs<2
    m,n=k+i,l+j
    ag<<[[m,n]]if m>0&&m<W&&n>0&&n<H&&ag&[m,n]==[]&&h==T[m][n]&&t>0
  }
end

$><<(H*W).times{|i|
    break(:YES)if ag&[Gx, Gy]!=[]
    break(:NO)if !(_=ag[i])
    candidate(*_,ag)}