h,w = map(int,input().split())
s=[]
for _ in range(h):
  s.append(str(input()))
for i in range(h):
  for j in range(w):
    flag=False
    if s[i][j]!="#":
      break
    for k in [-1,1]:
      if 0<=i+k<h:
        if s[i+k][j]=="#":
          flag=True
      if 0<=j+k<h:
        if s[i][j+k]=="#":
          flag=True
    if not flag:
      print("No")
      exit()
print("Yes")