Codeforces Round 375 (Div. 2)
F
st-Spanning Tree
Codeforces
2300
原题
← E→
翻译中…

You are given an undirected connected graph consisting of $*n*$ vertices and $*m*$ edges. There are no loops and no multiple edges in the graph.

翻译中…

You are also given two distinct vertices $*s*$ and $*t*$, and two values $*d*_{*s*}$ and $*d*_{*t*}$. Your task is to build any spanning tree of the given graph (note that the graph is not weighted), such that the degree of the vertex $*s*$ doesn't exceed $*d*_{*s*}$, and the degree of the vertex $*t*$ doesn't exceed $*d*_{*t*}$, or determine, that there is no such spanning tree.

翻译中…

The spanning tree of the graph $*G*$ is a subgraph which is a tree and contains all vertices of the graph $*G*$. In other words, it is a connected graph which contains $*n* - 1$ edges and can be obtained by removing some of the edges from $*G*$.

翻译中…

The degree of a vertex is the number of edges incident to this vertex.

翻译中…

Input

翻译中…

The first line of the input contains two integers $*n*$ and $*m*$ ($2 ≤ *n* ≤ 200 000$, $1 ≤ *m* ≤ *min*(400 000, *n*·(*n* - 1) / 2)$) — the number of vertices and the number of edges in the graph.

翻译中…

The next $*m*$ lines contain the descriptions of the graph's edges. Each of the lines contains two integers $*u*$ and $*v*$ ($1 ≤ *u*, *v* ≤ *n*$, $*u* ≠ *v*$) — the ends of the corresponding edge. It is guaranteed that the graph contains no loops and no multiple edges and that it is connected.

翻译中…

The last line contains four integers $*s*$, $*t*$, $*d*_{*s*}$, $*d*_{*t*}$ ($1 ≤ *s*, *t* ≤ *n*$, $*s* ≠ *t*$, $1 ≤ *d*_{*s*}, *d*_{*t*} ≤ *n* - 1$).

翻译中…

Output

翻译中…

If the answer doesn't exist print "No" (without quotes) in the only line of the output.

翻译中…

Otherwise, in the first line print "Yes" (without quotes). In the each of the next $(*n* - 1)$ lines print two integers — the description of the edges of the spanning tree. Each of the edges of the spanning tree must be printed exactly once.

翻译中…

You can output edges in any order. You can output the ends of each edge in any order.

翻译中…

If there are several solutions, print any of them.

翻译中…

样例

Input #1
3 3
1 2
2 3
3 1
1 2 1 1
Output #1
Yes
3 2
1 3
InputCopy OutputCopy
Input #2
7 8
7 4
1 3
5 4
5 7
3 2
2 4
6 1
1 2
6 4 1 4
Output #2
Yes
1 3
5 7
3 2
7 4
2 4
6 1
InputCopy OutputCopy
题目信息
题号
723F
时间限制
4 s
内存限制
256 MB
标签
并查集
图论
贪心
模拟

题面与样例版权归 Codeforces 及出题人所有;中文翻译由 AI 生成(CI 管线),如有出入请以原文为准。