H,W=map(int,input().split())
S=[0]*H
for i in range(H):
  S[i]=list(str(input()))

dx=[-1,0,1,0]
dy=[0,-1,0,1]

for i in range(H):
  for j in range(W):
    ok=0
    if S[i][j]=='#':
      for k in range(4):
        x=i+dx[k]
        y=j+dy[k]
        if 0<=x<W and 0<=y<H and S[y][x]=='#':
          ok=1
          break
      if ok==0:
        print('No')
        exit()
print('Yes') 

