# -*- coding:utf-8 -*-
H,W=map(int,input().split())
nx=[1,0,-1,0]
ny=[0,1,0,-1]

field=[]
for i in range(H):
  field.append(list(input()))

for n in range(W):
  for m in range(H):
    if field[n][m]=='.':
      continue
    
    hope=0
    for j in range(4):
      x=n+nx[j]
      y=m+ny[j]
      
      if x<0 or W<=x or y<0 or H<=y:
        continue

      if field[x][y]=='#':
        hope=1
      
    if hope==0:
      print('No')
      exit()

print('Yes')