h,w=map(int,input().split())
s=[list(input()) for i in range(h)]

dxy=[(-1,0),(0,1),(0,-1),(1,0)]
for i in range(h):
  for j in range(w):
    if s[i][j]=="#":
      f=False
      for x,y in dxy:
        
        if 0<=i+x<=h-1 and 0<=j+y<=w-1 and s[i+x][j+y]=="#":
          f=True
      
      if not f:
        print("No")
        break
        
        
if f:
  print("Yes")



