h,w,*a=list(open(0).read().split())
w,h=int(w),int(h)
for s in range(h-1):
  for t in range(w-1):
    if a[s][t]=="#":
      if a[s][t+1]=="#" or a[s+1][t]=="#":
        continue
      else:
        try:
          if a[s][t-1]=="#":
            continue
          else:
            print("No")
            exit()
        except IndexError:
          continue
s=h-1
for t in range(w-1):
  if a[s][t]=="#":
    if a[s][t+1]=="#" or a[s-1][t]=="#":
      continue
    else:
      try:
        if a[s][t-1]=="#":
          continue
        else:
          print("No")
          exit()
      except IndexError:
        continue
print("Yes")