H,W=map(int,input().split())
L=[list(input()) for _ in range(H)]

dhw=[(1,1),(1,-1),(-1,1),(-1,-1)]
P=[]
for h in range(H):
  for w in range(W):
    if L[h][w]=="#":
      flag=1
      for dh,dw in dhw:
        if not(0<=h+dh<H and 0<=w+dw<W and L[h+dh][w+dw]=="#"):
          flag=0
      if flag:
        P.append((h,w))

dp=[["."]*W for _ in range(H)]
for h,w in P:
  dp[h][w]="#"
  x=1
  flag=1
  while flag:
    for dh,dw in dhw:
      if not(0<=h+dh*x<H and 0<=w+dw*x<W):
        flag=0
    if flag:
      for dh,dw in dhw:
        dp[h+dh*x][w+dw*x]="#"
    x+=1
print("Yes" if L==dp else "No")