import sys
h,w = map(int,input().split())
s = [list(input()) for i in range(h)]
for i in range(w-1):
  for l in range(h-1):
    if s[i][l] == "#":
      if s[i-1][l] == "#" :
        continue
      elif s[i][l-1] == "#":
        continue
      elif s[i][l+1] == "." and s[i+1][l] == ".":
        print("No")
        sys.exit()
    
      
print("Yes")
      