h,w=map(int,input().split())
s=["."*(w+2)]
for i in range(h):s.append("."+input()+".")
s.append("."*(w+2))
ans="Yes"
for i in range(1,h+1):
  for j in range(1,w+1):
    if s[i-1][j]+s[i+1][j]+s[i][j-1]+s[i][j+1]=="....":ans="No"
print(ans)