H, W = map(int, input().split())
s = [input() for _ in range(H)]
#print(s)

f1 = True
for i in range(H):
  if not f1:
    break
  for j in range(W):
    if not f1:
      break
    if s[i][j] == '.':
      continue
    f = False
    if i >= 1 and s[i-1][j] == '#':
      f = True
    if j <= W-2 and s[i][j+1] == '#':
      f = True
    if i <= H-2 and s[i+1][j] == '#':
      f = True
    if j >= 1 and s[i][j-1] == '#':
      f = True
    if not f:
      f1 = False

#print(s)
if f:
  print('Yes')
else:
  print('No')
