h,w=map(int,input().split())
d=[['.']*(w+2) for j in range(h+2)]
for hh in range(h):
  moji=input()
  for ww in range(w):
    d[hh+1][ww+1]=moji[ww]
for k in range(1,h+1):
  for l in range(1,w+1):
    if all(aa=='.' for aa in [d[k-1][l],d[k+1][l],d[k][l-1],d[k][l+1]]):
      print('No')
      exit()
print('Yes')