import sys
h,w=map(int,input().split())
lst=[[0 for i in range(w)]for j in range(h)]
for i in range(h):
  s=input().split()
  for j in range(len(s)):
    if s[j]=='#':
      lst[i][j]=1

for j in range(h):
  for k in range(w-2):
    if lst[j][k]*lst[j][k+1]==0 and lst[j][k+1]*lst[j][k+2]==0:
      print('No')
      sys.exit()
    
for k in range(w):
  for j in range(h-2):
    if lst[j][k]*lst[j+1][k]==0 and lst[j+1][k]*lst[j+2][k]==0:
      print('No')
      sys.exit()
    
print('Yes')
