Thinking Step 2: 推理第一个人。如果他不想要，他会直接说“不”（因为只要有一个不要，全称命题为假）。他说“不知道”，说明他自己想要，但他不确定后面两个人想不想要。
- 父节点i的左子: 2*i+1, 右子: 2*i+2，这一点在safew官方版本下载中也有详细论述
Councils blamed the delay on demand for new specialist vehicles, as well as issues with funding despite more than £340m in grants from Defra. You can find out what is happening with your local council's collections further down in this story.，更多细节参见safew官方版本下载
Then Fayers' team will have to ask the environmental regulators for final approval.
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