B'Lord Omkar would like to have a tree with n nodes ( 3 <= n <= 10^5 ) and has asked his disciples to construct the tree. However, Lord Omkar has created m ( mathbf{1 <= m < n} ) restrictions to ensure that the tree will be as heavenly as possible. A tree with n nodes is an connected undirected graph with n nodes and n-1 edges. Note that for any two nodes, there is exactly one simple path between them, where a simple path is a path between two nodes that does not contain any node more than once. Here is an example of a tree: A restriction consists of 3 pairwise distinct integers, a , b , and c ( 1 <= a,b,c <= n ). It signifies that node b cannot lie on the simple path between node a and node c . Can you help Lord Omkar and become his most trusted disciple? You will need to find heavenly trees for multiple sets of restrictions. It can be shown that a heavenly tree will always exist for any set of restrictions under the given constraints. Each test contains multiple test cases. The first line contains the number of test cases t ( 1 <= q t <= q 10^4 ). Description of the test cases follows. The first line of each test case contains two integers, n and m ( 3 <= q n <= q 10^5 , mathbf{1 <= q m < n} ), representing the size of the tree and the number of restrictions. The i -th of the next m lines contains three integers a_i , b_i , c_i ( 1 <= a_i, b_i, c_i <= n , a , b , c are distinct), signifying that node b_i cannot lie on the simple path between nodes a_i and c_i . It is guaranteed that the sum of n across all test cases will not exceed 10^5 . For each test case, output n-1 lines representing the n-1 edges in the tree. On each line, output two integers u and v ( 1 <= u, v <= n , u neq v ) signifying that there is an edge between'...