program main
  implicit none
  integer::H,W,i,j,hoffset,woffset,blacknum
  integer,allocatable::mas(:,:),nuri(:,:)
  character*50,allocatable::S(:)
  integer,parameter::white=0,black=1,red=2,blue=3
  character,parameter::cwhite='.',cblack='#'
  read *,H,W
  allocate(S(H))
  allocate(mas(W,H),nuri(W,H))
  read *,S
  do i=1, H
     do j=1,W
        if(S(i)(j:j).eq.cwhite) then
           mas(j,i) = white
        else
           mas(j,i) = black
        end if
     end do
  end do

  blacknum = COUNT(mas.eq.black)
  if(blacknum.eq.0.or.MOD(blacknum, 2).eq.1) then
     print '(a)', "NO"
     return
  end if

  do hoffset=-(H-1), H-1
     do woffset=-(W-1), W-1
        if(hoffset.eq.0.and.woffset.eq.0) cycle
        nuri = mas
        do i=1,H
           do j=1,W
              if(j+woffset.le.0.or.j+woffset.gt.W.or. &
                 i+hoffset.le.0.or.i+hoffset.gt.H) then
                 cycle
              end if

              if(nuri(j,i).eq.black.and. &
                 nuri(j+woffset,i+hoffset).eq.black) then
                 nuri(j,i) = red
                 nuri(j+woffset,i+hoffset) = blue
              end if
!              print *,j,i
!              call printer(nuri,H,W)
           end do
        end do
        if(ANY(nuri.eq.black)) then
           continue
        else
           print '(a)', "YES"
           return
        end if
     end do
  end do

  print '(a)', "NO"
contains
  subroutine printer(nuri, H, W)
    integer,allocatable::nuri(:,:)
    integer,parameter::white=0,black=1,red=2,blue=3
    character,parameter::cwhite='.',cblack='#',cred='*',cblue='%'
    integer::i,j,H,W
    character::c
    do i=1,H
       do j=1,W
          select case(nuri(j,i))
          case(white)
             c = cwhite
          case(black)
             c = cblack
          case(red)
             c = cred
          case(blue)
             c = cblue
          end select
          write (*,'(a)',advance='no') c
       end do
       write (*,*)
    end do
  end subroutine printer
end program main