n,m=map(int,input().split())
hoge=[[0 for i in range(n+2)] for j in range(m+2)]
for i in range(m):
  sss=input()
  for j in range(n):
    if(sss[j]=="#"):
      hoge[1+i][1+j]=1
    
flag=True
for i in range(m):
  for j in range(n):
    if(hoge[1+i][1+j]==1):
      ans=0
      ans+=hoge[i][1+j]+hoge[1+i][j]+hoge[2+i][1+j]+hoge[1+i][2+j]
      if(ans==0):
        flag=False
        
if(flag):
  print("Yes")
else:
  print("No")