def grinp(h):
  ret=[]
  for i in range(h):
    ret.append(list(input()))
  return ret
h,w=map(int,input().split())
grid=grinp(h)
fa=False
for i in range(h):
  for j in range(w):
    if grid[i][j]==".":
      continue
    fl=0
    if i!=0 and grid[i-1][j]=="#":
      fl+=1
    if i!=h-1 and grid[i+1][j]=="#":
      fl+=1
    if j!=0 and grid[i][j-1]=="#":
      fl+=1
    if j!=h-1 and grid[i][j+1]=="#":
      fl+=1
    if fl==0:
      fa=True
      break
  if fa:
    break
if fa:
  print("No")
else:
  print("Yes")
    