Please, try EDU on Codeforces! New educational section with videos, subtitles, texts, and problems.
×

Virtual contest is a way to take part in past contest, as close as possible to participation on time. It is supported only ICPC mode for virtual contests.
If you've seen these problems, a virtual contest is not for you - solve these problems in the archive.
If you just want to solve some problem from a contest, a virtual contest is not for you - solve this problem in the archive.
Never use someone else's code, read the tutorials or communicate with other person during a virtual contest.

No tag edit access

C. Tree Diameter

time limit per test

4 secondsmemory limit per test

256 megabytesinput

standard inputoutput

standard outputThere is a weighted tree with $$$n$$$ nodes and $$$n-1$$$ edges. The nodes are conveniently labeled from $$$1$$$ to $$$n$$$. The weights are positive integers at most $$$100$$$. Define the distance between two nodes to be the sum of edges on the unique path between the nodes. You would like to find the diameter of the tree. Diameter is the maximum distance between a pair of nodes.

Unfortunately, the tree isn't given to you, but you can ask some questions about it. In one question, you can specify two nonempty disjoint sets of nodes $$$p$$$ and $$$q$$$, and the judge will return the maximum distance between a node in $$$p$$$ and a node in $$$q$$$. In the words, maximum distance between $$$x$$$ and $$$y$$$, where $$$x \in p$$$ and $$$y \in q$$$. After asking not more than $$$9$$$ questions, you must report the maximum distance between any pair of nodes.

Interaction

Each test contains multiple test cases. The first line contains the number of test cases $$$t$$$ ($$$1 \le t \le 1\,000$$$). Description of the test cases follows.

The first line of each test case contains an integer $$$n$$$ ($$$2 \leq n \leq 100$$$) — the number of nodes in the tree.

To ask a question, print "$$$k_1\ k_2\ a_1\ a_2\ \ldots\ a_{k_1}\ b_1\ b_2\ \ldots\ b_{k_2}$$$" $$$(k_1, k_2 \geq 1$$$ and $$$k_1+k_2 \leq n$$$). These two sets must be nonempty and disjoint. The judge will respond with a single integer $$$\max_{p,q} dist(a_p, b_q)$$$. If you ever get a result of $$$-1$$$ (because you printed an invalid query), exit immediately to avoid getting other verdicts.

After printing a query do not forget to output end of line and flush the output. Otherwise, you will get Idleness limit exceeded. To do this, use:

- fflush(stdout) or cout.flush() in C++;
- System.out.flush() in Java;
- flush(output) in Pascal;
- stdout.flush() in Python;
- see documentation for other languages.

When you are ready to answer, print "$$$-1\ d$$$", where $$$d$$$ is the maximum shortest distance over all pairs of nodes.

You can only ask at most $$$9$$$ questions per test case.

Hack Format

To hack, use the following format. Note that you can only hack with one test case.

The first line should contain a single integer $$$t$$$ ($$$t=1$$$).

The second line should contain a single integer $$$n$$$ ($$$2 \leq n \leq 100$$$).

Each of the next $$$n-1$$$ lines should contain three integers $$$a_i, b_i, c_i$$$ ($$$1\leq a_i, b_i\leq n$$$, $$$1 \leq c_i \leq 100$$$). This denotes an undirected edge between nodes $$$a_i$$$ and $$$b_i$$$ with weight $$$c_i$$$. These edges must form a tree.

Example

Input

2 5 9 6 10 9 10 2 99

Output

1 4 1 2 3 4 5 1 4 2 3 4 5 1 1 4 3 4 5 1 2 1 4 4 5 1 2 3 1 4 5 1 2 3 4 -1 10 1 1 1 2 -1 99

Note

In the first example, the first tree looks as follows:

In the first question, we have $$$p = {1}$$$, and $$$q = {2, 3, 4, 5}$$$. The maximum distance between a node in $$$p$$$ and a node in $$$q$$$ is $$$9$$$ (the distance between nodes $$$1$$$ and $$$5$$$).

The second tree is a tree with two nodes with an edge with weight $$$99$$$ between them.

Codeforces (c) Copyright 2010-2020 Mike Mirzayanov

The only programming contests Web 2.0 platform

Server time: Jul/08/2020 08:22:47 (i1).

Desktop version, switch to mobile version.

Supported by

User lists

Name |
---|