H, W = map(int, input().split())
S = ['.'*(W+2)] + ['.' + input() + '.' for _ in range(H)] + ['.'*(W+2)]
flg = False
for i in range(1, H+1):
  for j in range(1, W+1):
    if S[i][j] == '#':
      cnt = 0
      if S[i][j-1] == '.':
        cnt += 1
      if S[i][j+1] == '.':
        cnt += 1
      if S[i-1][j] == '.':
        cnt += 1
      if S[i+1][j] == '.':
        cnt += 1
      flg = (cnt == 4)
if flg:
  print("No")
else:
  print("Yes")