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):
    if lst[j][k]==1:
      if lst[max(j-1,0)][k]==1 or lst[min(j+1,h-1)][k]==1 or lst[j][max(0,k-1)]==1 or lst[j][min(k+1,w-1)]==1:
        pass
      else:
        print('No')
        sys.exit()

print('Yes')