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