import sys
h,w = map(int,input().split())
s = ['']*h
for i in range(h):
  s[i] = input()
 
black = False
for i in range(h):
  for j in range(w):
    if s[i][j] == '#':
      black = True
      if j != w - 1:
        if s[i][j + 1] == '#':
          continue
      if  j != 0:
        if s[i][j - 1] == '#':
          continue
      if i != h - 1:
        if s[i + 1][j] == '#':
          continue
      if i != 0:
        if s[i - 1][j] == '#':
          continue
      print('No')
      sys.exit()       
if black:
  print('Yes')
else:
  print('No')