h,w=map(int,input().split())
a=[]
for i in range(h):
  a.append(list("."+(input())+"."))
a.insert(0,["."]*(h+2))
a.append(["."]*(h+2))
flg = True
for i in range(h+2):
  for j in range(w+2):
    if a[i][j] == "#":
      for (k,l) in ((i,j+1),(i,j-1),(i+1,j),(i-1,j)):
        if a[k][l] != "#":
          cnt+=1
          if cnt == 4:
            flg = False
    cnt=0
if flg:
  print("Yes")
else:
  print("No")