program main
  implicit none
  integer :: h,w,i,j
  integer,allocatable :: x(:,:)
  character(50) :: s

  read(*,*) h,w
  allocate(x(0:h+1,0:w+1))
  x(:,:)=0

  do i=1,h
     read(*,*) s
     do j=1,w
        if(s(j:j)=='#')then
           x(i,j)=1
        else
           x(i,j)=0
        endif
     enddo
  enddo

  do i=1,h
     do j=1,w
        if(x(i,j)/=1)then
           exit
        else if(x(i,j-1)==1)then
           exit
        else if(x(i,j+1)==1)then
           exit
        else if(x(i+1,j)==1)then
           exit
        else if(x(i-1,j)==1)then
           exit
        else
           write(*,*) 'No'
           go to 100
        endif
     enddo
  enddo

  write(*,*) 'Yes'

100 end program main