h, w = map(int, input().split())
hor = '.' * (h+2)
board = [hor] * (w+2)
for i in range(1, h+1):
    board[i] = '.' + input() + '.'

# print(board)
ans = "Yes"
for i in range(1, h+1):
    for j in range(1, w+1):
        if board[i][j] == '#':
            if board[i+1][j] == "." and\
            board[i][j+1] == "." and\
            board[i][j-1] == "." and\
            board[i-1][j] == ".":
                ans = "No"
                break

print(ans)
