A. Twice
implementation
Kinich wakes up to the start of a new day. He turns on his phone, checks his mailbox, and finds a mysterious present. He decides to unbox the present.Kinich unboxes an array \(a\) with \(n\) integers. Initially, Kinich's score is \(0\). He will perform the following operation any number of times: Select two indices \(i\) and \(j\) \((1 \leq i < j \leq n)\) such that neither \(i\) nor \(j\) has been chosen in any previous operation and \(a_i = a_j\). Then, add \(1\) to his score. Output the maximum score Kinich can achieve after performing the aforementioned operation any number of times.
The first line contains an integer \(t\) (\(1 \leq t \leq 500\)) — the number of test cases.The first line of each test case contains an integer \(n\) (\(1 \leq n \leq 20\)) — the length of \(a\).The following line of each test case contains \(n\) space-separated integers \(a_1, a_2, \ldots, a_n\) (\(1 \leq a_i \leq n\)).
For each test case, output the maximum score achievable on a new line.
In the first and third testcases, Kinich cannot perform any operations.In the second testcase, Kinich can perform one operation with \(i=1\) and \(j=2\).In the fourth testcase, Kinich can perform one operation with \(i=1\) and \(j=4\).