H,W = map(int,input().split())
arr = []

for i in range(H):
  S = list(input())
  arr.append(S)
  
ck = 0
for i in range(H):
  for j in range(W):
    if arr[i][j] == "#":
      if i != 0:
        a = arr[i-1][j]
      else:
        a = "."
      if i != H-1:
        b = arr[i+1][j]
      else:
        b = "."
      if j != 0:
        c = arr[i][j-1]
      else:
        c = "."
      if j != W-1:
        d = arr[i][j+1]
      else:
        d = "."
    if a == "." and b == "." and c == "." and d == ".":
      ck = 1
      
if ck == 1:
  print("No")
else:
  print("Yes")