|Codeforces Round #236 (Div. 2)|
Let's call an undirected graph of n vertices p-interesting, if the following conditions fulfill:
A subgraph of a graph is some set of the graph vertices and some set of the graph edges. At that, the set of edges must meet the condition: both ends of each edge from the set must belong to the chosen set of vertices.
Your task is to find a p-interesting graph consisting of n vertices.
The first line contains a single integer t (1 ≤ t ≤ 5) — the number of tests in the input. Next t lines each contains two space-separated integers: n, p (5 ≤ n ≤ 24; p ≥ 0; ) — the number of vertices in the graph and the interest value for the appropriate test.
It is guaranteed that the required graph exists.
For each of the t tests print 2n + p lines containing the description of the edges of a p-interesting graph: the i-th line must contain two space-separated integers a i, b i (1 ≤ a i, b i ≤ n; a i ≠ b i) — two vertices, connected by an edge in the resulting graph. Consider the graph vertices numbered with integers from 1 to n.
Print the answers to the tests in the order the tests occur in the input. If there are multiple solutions, you can print any of them.