Fanfan has a valid bracket sequence $$$s$$$ containing $$$n$$$ bracket pairs, and all bracket pairs are numbered from $$$1$$$ to $$$n$$$. The numbering is assigned according to the order in which the left brackets appear: the first left bracket that appears and its matching right bracket form bracket pair $$$1$$$, the second left bracket that appears and its matching right bracket form bracket pair $$$2$$$, and so on.
Based on this valid bracket sequence, Fanfan constructs a binary tree according to the following rules:
For the bracket pair numbered $$$p$$$ (whose corresponding bracket positions in the sequence are $$$s_i$$$ and $$$s_j$$$, where $$$s_i$$$ is a left bracket and $$$s_j$$$ is the matching right bracket), we examine $$$s_{i+1}$$$ and $$$s_{j+1}$$$:
If $$$s_{i+1}$$$ is a left bracket, then let the corresponding bracket pair be numbered $$$l$$$, and make $$$l$$$ the left child of $$$p$$$;
If $$$s_{j+1}$$$ is a left bracket, then let the corresponding bracket pair be numbered $$$r$$$, and make $$$r$$$ the right child of $$$p$$$.
Now, Fanfan has lost the original bracket sequence $$$s$$$, but the constructed binary tree structure is still available. Your task is to reconstruct the original valid bracket sequence $$$s$$$ from the given binary tree.
The first line contains an integer $$$t$$$ ($$$1 \le t \le 10^4$$$), denoting the number of test cases.
For each test case, the first line contains an integer $$$n$$$ ($$$1 \leq n \leq 10^5$$$), denoting the number of bracket pairs.
The next $$$n$$$ lines each contain two integers $$$l$$$ and $$$r$$$, representing the left child and right child of each bracket pair numbered from $$$1$$$ to $$$n$$$, respectively. If a bracket pair has no left child or no right child, then the corresponding $$$l$$$ or $$$r$$$ is $$$0$$$.
It is guaranteed that the sum of all $$$n$$$ over a single test file does not exceed $$$2 \cdot 10^5$$$.
For each test case, output a line containing a string consisting of $$$($$$ and $$$)$$$, representing the reconstructed valid bracket sequence $$$s$$$.
1 3 2 3 0 0 0 0
(())()
The binary tree structure corresponding to the sample input is as follows:
The bracket pair numbered $$$1$$$ has left child $$$2$$$ and right child $$$3$$$;
The bracket pairs numbered $$$2$$$ and $$$3$$$ have no children.
The corresponding valid bracket sequence is $$$(())()$$$, where:
Bracket pair $$$1$$$ consists of the $$$1$$$st character (a left bracket) and the $$$4$$$th character (a right bracket);
Bracket pair $$$2$$$ consists of the $$$2$$$nd character (a left bracket) and the $$$3$$$rd character (a right bracket);
Bracket pair $$$3$$$ consists of the $$$5$$$th character (a left bracket) and the $$$6$$$th character (a right bracket).
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