#P1033E. Hidden Bipartite Graph

    ID: 5145 Type: RemoteJudge 4000ms 256MiB Tried: 0 Accepted: 0 Difficulty: 10 Uploaded By: Tags>binary searchconstructive algorithmsdfs and similargraphsinteractive*2800

Hidden Bipartite Graph

Description

Bob has a simple undirected connected graph (without self-loops and multiple edges). He wants to learn whether his graph is bipartite (that is, you can paint all vertices of the graph into two colors so that there is no edge connecting two vertices of the same color) or not. As he is not very good at programming, he asked Alice for help. He does not want to disclose his graph to Alice, but he agreed that Alice can ask him some questions about the graph.

The only question that Alice can ask is the following: she sends ss — a subset of vertices of the original graph. Bob answers with the number of edges that have both endpoints in ss. Since he doesn't want Alice to learn too much about the graph, he allows her to ask no more than 2000020000 questions. Furthermore, he suspects that Alice might introduce false messages to their communication channel, so when Alice finally tells him whether the graph is bipartite or not, she also needs to provide a proof — either the partitions themselves or a cycle of odd length.

Your task is to help Alice to construct the queries, find whether the graph is bipartite.

The first line contains a single integer nn (1n6001 \leq n \leq 600) — the number of vertices in Bob's graph.

Interaction

First, read an integer nn (1n6001\leq n\leq 600) — the number of vertices in Bob's graph.

To make a query, print two lines. First of which should be in the format "? k" (1kn1 \leq k \leq n), where kk is the size of the set to be queried. The second line should contain kk space separated distinct integers s1,s2,,sks_1, s_2, \dots, s_k (1sin1 \leq s_i \leq n) — the vertices of the queried set.

After each query read a single integer mm (0mn(n1)20 \leq m \leq \frac{n(n-1)}{2}) — the number of edges between the vertices of the set {si}\{s_i\}.

You are not allowed to ask more than 2000020000 queries.

If m=1m = -1, it means that you asked more queries than allowed, or asked an invalid query. Your program should immediately terminate (for example, by calling exit(0)). You will receive Wrong Answer; it means that you asked more queries than allowed, or asked an invalid query. If you ignore this, you can get other verdicts since your program will continue to read from a closed stream.

After printing a query do not forget to print 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 know the answer, you need to print it.

The format of the answer depends on whether the graph is bipartite or not.

If the graph is bipartite, print two lines. The first should contain the letter "Y" (short for "YES") followed by a space, and then a single integer ss (0sn0 \leq s \leq n) — the number of vertices in one of the partitions. Second line should contain ss integers a1,a2,,asa_1, a_2, \dots, a_s — vertices belonging to the first partition. All aia_i must be distinct, and all edges in the main graph must have exactly one endpoint in the set {ai}\{a_i\}.

If the graph is not bipartite, print two lines. The first should contain the letter "N" (short for "NO") followed by a space, and then a single integer ll (3ln3 \leq l \leq n) — the length of one simple cycle of odd length. Second line should contain ll integers c1,c2,,clc_1, c_2, \dots, c_l — the vertices along the cycle. It must hold that for all 1il1 \leq i \leq l, there is an edge {ci,c(imod  l)+1}\{c_i, c_{(i \mod l)+1}\} in the main graph, and all cic_i are distinct.

If there are multiple possible answers, you may print any of them.

Hacks format For hacks, use the following format:

The first line contains two integers nn and m (1n600,0mn(n1)2)m~(1 \leq n \leq 600, 0 \leq m \leq \frac{n(n-1)}{2}) — the number of vertices and edges of the graph, respectively.

Each of the next mm lines contains two integers uiu_i and vi (1ui,vin)v_i~(1 \leq u_i, v_i \leq n) mean that there is an edge between uiu_i and viv_i. There must not be any multiple edges, no loops, and the graph must be connected.

For example, you need to use this test to get the first sample:


4 4
4 1
1 3
3 2
2 4

Input

The first line contains a single integer nn (1n6001 \leq n \leq 600) — the number of vertices in Bob's graph.

Sample Input 1

4
4
0
1
1
1
0

Sample Output 1

? 4 
1 2 3 4
? 2
1 2
? 2
1 3
? 2
1 4
? 2
2 4
? 2
3 4
Y 2
1 2

Sample Input 2

4
4
3

Sample Output 2

? 4
1 4 2 3
? 3
1 2 4
N 3
2 1 4

Note

In the first case, Alice learns that there are 44 edges in the whole graph. Over the course of the next three queries, she learns that vertex 11 has two neighbors: 33 and 44. She then learns that while vertex 22 is adjacent to 44, the vertex 33 isn't adjacent to 44. There is only one option for the remaining edge, and that is (2,3)(2, 3). This means that the graph is a cycle on four vertices, with (1,2)(1, 2) being one partition and (3,4)(3, 4) being the second. Here, it would be also valid to output "3 4" on the second line.

In the second case, we also have a graph on four vertices and four edges. In the second query, Alice learns that there are three edges among vertices (1,2,4)(1, 2, 4). The only way this could possibly happen is that those form a triangle. As the triangle is not bipartite, Alice can report it as a proof. Notice that she does not learn where the fourth edge is, but she is able to answer Bob correctly anyway.