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

ans = "Yes"
judge = 0

for i in range(w):
  for j in range(h):
    sign = 0
    
    if s[j][i] == ".":
      continue
    
    if (0<j-1) and (s[j-1][i] == "#"):
      sign = 1
    
    if (0<i-1) and (s[j][i-1] == "#"):
      sign = 1
      
    if (j+1<h) and (s[j+1][i] == "#"):
      sign = 1
      
    if (i+1<w) and (s[j][i+1] == "#"):
      sign = 1
      
    if sign != 1:
      ans = "No"
      judge = 1
      break
  
  if judge == 1:
    break
      
print(ans)