import math
H, W = map(int, input().split())
s = []
flag = 0
ans = "No"
for i in range(W):
  s.append(list(input()))
for i in range(H):
  for j in range(W):
    if flag == 0:
      if s[i][j] == "#":
        if s[max(0, i - 1)][j] == "#" or s[i][max(0, j - 1)] == "#" or s[min(H - 1, i + 1)][j] == "#" or s[i][min(W - 1, j + 1)] == "#":
          continue
        else:
          flag += 1
if flag == 0:
  ans = "Yes"
print(ans)