import numpy as np
 
H, W = map(int, input().split())
S = np.array([list(input()) for _ in range(H)])

for i in range(H):
  for j in range(W):
    if S[i, j] == '#':
      if np.sum(np.concatenate(S[i-1:i, j], S[i, j-1:j], S[i+1:i, j], S[i, j+1:j]) == '#') == 0:
        print('No')
        break
else:
  print('Yes')