h,w=map(int,input().split())
s=[list(input()) for i in range(h)]
flag=True
count=0
for i in range(h):
  for j in range(w):
    if s[i][j]=="#":
      if i>0 and s[i-1][j]!="#":
        flag=False
      elif i>0 and s[i-1][j]=="#":
        flag=True
        break
        
      if i<(h-1) and s[i+1][j]!="#":
        flag=False
      elif i<(h-1) and s[i+1][j]=="#":
        flag=True
        break
        
      if j>0 and s[i][j-1]!="#":
        flag=False
      elif j>0 and s[i][j-1]=="#":
        flag=True
        break
        
      if j<(w-1) and s[i][j+1]!="#":
        flag=False
      elif j<(w-1) and s[i][j+1]=="#":
        flag=True
        break
    else:
      count+=1
        
if h==1 and w==1:
  if s[0][0]=="#":
    flag=False
    
if count==(h*w):
  flag=True
  
if flag:
  print("Yes")
else:
  print("No")