There are multiple test cases. The first line of input contains an integer T, indicating the number of test cases. For each test case:
The first line contains an integer n (1≤n≤1000) -- the number of triangle to construct.
Each of the next 3n lines contains two integers xi and yi (?109≤xi,yi≤109).
It is guaranteed that the sum of all n does not exceed 10000.
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这个题目，因为output 是输出每个点的索引，所以定义一个结构体，放X Y num num为索引，然后根据X（或者Y） 用sort， cmp排序，再每隔三个点输出一次num就可以了。难点是在对题意的理解上。
