H,W=[int(s) for s in input().split()]
cam_ls=[ "." for _ in range(H+2)]
for j in range(H+1):
  cam_ls[0]=cam_ls[0]+"."
  cam_ls[H+1]=cam_ls[H+1]+"."
for i in range(1,H+1):
  cam_ls[i]=cam_ls[i]+input()+"."
  
def pos(h,w):
  if cam_ls[h][w]==".":
    return 1
  elif (cam_ls[h+1][w]=="." and
        cam_ls[h-1][w]=="." and
        cam_ls[h][w+1]=="." and
        cam_ls[h][w-1]=="."):
    return 0
  else:
    return 1

ans=1
for i in range(1,H+1):
  for j in range(1,W+1):
    ans*=pos(i,j)
if ans==1:
  print("Yes")
else:
  print("No")

