H, W = sorted(map(int,input().split()))
C = [input() for _ in range(H)]

ans = "Yes"
for i in range(H):
  for j in range(W):
    if(C[i][j] == "."):
      continue
    if(i > 0 and C[i-1][j] == "#"):
      continue
    if(i+1 < H and C[i+1][j] == "#"):
      continue
    if(j > 0 and C[i][j-1] == "#"):
      continue
    if(j+1 < W and C[i][j+1] == "#"):
      continue
    ans = "No"
print(ans)