9. In one line, 19 numbers were written. The sum of any three consecutive numbers is positive. Can the sum of all 19 numbers be negative?
9. Consider, for example, the sequence of numbers $\underbrace{-7,4,4, \ldots,-7,4,4,-7}_{19 \text { numbers }}$. The sum of any 3 consecutive numbers in this sequence is 1, i.e., positive, while the sum of all 19 numbers is -1, i.e., negative. Answer: It can. Find another similar example.