H,W=(int(i) for i in input().split(' '))
s=[]
for h in range(H):
  s+=[input()]
for h in range(H):
  for w in range(W):
    if s[h][w]=='#':
      if h>0:
        if s[h-1][w]=='#':
          break
      if w>0:
        if s[h][w-1]=='#':
          break
      if w<W-1:
        if s[h][w+1]=='#':
          break
      if h<H-1:
        if s[h+1][w]=='#':
          break
      print('No')
      exit()
print('Yes')