H, W = map(int,input().split())
S = [list(input()) for _ in range(H)]
ans = "Yes"
for i in range(H):
  for j in range(W):
    if(S[i][j] == "#"):
      if(i != 0 and S[i-1][j] == "#"):
        continue
      if(i != H and S[i+1][j] == "#"):
        continue
      if(j != 0 and S[i][j-1] == "#"):
        continue
      if(j != W and S[i][j+1] == "#"):
        continue
      ans = "No"
print(ans)