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(1,h-1):
  for k in range(1,w-1):
    if lst[j][k]==1:
      if lst[j-1][k]==1 or lst[j+1][k]==1 or lst[j][k-1]==1 or lst[j][k+1]==1:
        pass
      else:
        print('No')
        sys.exit()

print('Yes')
