H, W = map(int, input().split())
S = ['.'*(W+2)] + ['.' + input() + '.' for _ in range(H)] + ['.'*(W+2)]
for i in range(1, H+1):
  for j in range(1, W+1):
    if S[i][j] == '#':
      for x, y in [(-1, 0), (1, 0), (0, -1), (0, 1)]:
        if S[i+x][j+y] == '#':
          break
      else:
        print('No')
        return
else:
  print('Yes')
