A9439. Searching for Graph

Let's call an undirected graph of $n$ vertices $p$ -interesting, if the following conditions fulfill:

- the graph contains exactly $2n+p$ edges;
- the graph doesn't contain self-loops and multiple edges;
- for any integer $k$ ( $1<=k<=n$ ), any subgraph consisting of $k$ vertices contains at most $2k+p$ edges.

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.