P25868 [AtCoder] Simple path
普及-
题目描述

Problem Statement

There is a tree T with N vertices. The $i-th edge (1\leq i\leq N-1) connects vertex U_i$ and vertex V_i.
You are given two different vertices X and Y in T.
List all vertices along the simple path from vertex X to vertex Y in order, including endpoints.
It can be proved that, for any two different vertices a and b in a tree, there is a unique simple path from a to b.
What is a simple path?
For vertices X and Y in a graph G, a path from vertex X to vertex Y is a sequence of vertices $v_1,v_2, \ldots, v_k$ such that v_1=X, v_k=Y, and v_i and v_{i+1} are connected by an edge for each $1\leq i\leq k-1$.
Additionally, if all of $v_1,v_2, \ldots, v_k$ are distinct, the path is said to be a simple path from vertex X to vertex Y.

Input

The input is given from Standard Input in the following format:
N X Y
U_1 V_1
U_2 V_2
$\vdots$
U_{N-1} V_{N-1}

Output

Print the indices of all vertices along the simple path from vertex X to vertex Y in order, with spaces in between.

Constraints

  • $1\leq N\leq 2\times 10^5$
  • $1\leq X,Y\leq N$
  • $X\neq Y$
  • $1\leq U_i,V_i\leq N$
  • All values in the input are integers.
  • The given graph is a tree.

Sample Input 1

5 2 5
1 2
1 3
3 4
3 5

Sample Output 1

2 1 3 5

The tree T is shown below. The simple path from vertex 2 to vertex 5 is $2 \to$ $1 \to$ $3 \to$ 5.
Thus, 2,1,3,5 should be printed in this order, with spaces in between.

Sample Input 2

6 1 2
3 1
2 5
1 2
4 1
2 6

Sample Output 2

1 2

The tree T is shown below.

输入格式

见题面 Input 部分

输出格式

见题面 Output 部分

样例输入
5 2 5 1 2 1 3 3 4 3 5
样例输出
2 1 3 5