题目描述
Problem Statement
There is a simple graph with N vertices numbered 1 to N and M edges numbered 1 to M. Edge i connects vertices u_i and v_i.
Each vertex has one lamp on it. Initially, all the lamps are off.
Determine whether it is possible to turn exactly K lamps on by performing the following operation between 0 and M times, inclusive.
- Choose one edge. Let u and v be the endpoints of the edge. Toggle the states of the lamps on u and v. That is, if the lamp is on, turn it off, and vice versa.
If it is possible to turn exactly K lamps on, print a sequence of operations that achieves this state.
Input
The input is given from Standard Input in the following format:
N M K
u_1 v_1
u_2 v_2
$\vdots$
u_M v_M
Output
If it is impossible to turn exactly K lamps on, print No.
Otherwise, first print Yes, and then print a sequence of operations in the following format:
X
$e_1 e_2 \dots e_X$
Here, X is the number of operations, and e_i is the number of the edge chosen in the i-th operation. These must satisfy the following:
- $0 \leq X \leq M$
- $1 \leq e_i \leq M$
If multiple sequences of operations satisfy the conditions, any of them will be considered correct.
Constraints
- $1 \leq N \leq 2 \times 10^5$
- $0 \leq M \leq \min\left( 2 \times 10^5, \frac{N(N-1)}{2} \right)$
- $0 \leq K \leq N$
- $1 \leq u_i < v_i \leq N$
- The given graph is simple.
- All input values are integers.
Sample Input 1
5 5 4
1 2
1 3
2 4
3 5
1 5
Sample Output 1
Yes
3
3 4 5
If we operate according to the sample output, it will go as follows:
- Choose edge 3. Turn on the lamps on vertex 2 and vertex 4.
- Choose edge 4. Turn on the lamps on vertex 3 and vertex 5.
- Choose edge 5. Turn on the lamp on vertex 1 and turn off the lamp on vertex 5.
After completing all operations, the lamps on vertices 1, 2, 3, and 4 are on. Therefore, this sequence of operations satisfies the conditions.
Other possible sequences of operations that satisfy the conditions include X = 4, (e_1,e_2,e_3,e_4) = (3,4,3,1). (It is allowed to choose the same edge more than once.)
Sample Input 2
5 5 5
1 2
1 3
2 4
3 5
1 5
Sample Output 2
No
Sample Input 3
10 10 6
2 5
2 6
3 5
3 8
4 6
4 8
5 9
6 7
6 10
7 9
Sample Output 3
Yes
3
10 9 6
输入格式
见题面 Input 部分
输出格式
见题面 Output 部分