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QOJ

Time Limit: 5 s Memory Limit: 2048 MB Total points: 100 Hackable ✓
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Source: Library Checker

给定一张 $N$ 个点 $M$ 条边的无向图,你需要判定其是否为一张弦图

如果其是弦图,你还需要给出任意完美消除序列。如果不是弦图,你需要给出其长度大于等于 $4$ 且不包含弦的环。

输入格式

输入的第一行包含两个整数 $N$ 和 $M$。

接下来 $M$ 行,每行两个整数 $x, y$,描述一条边。保证图中没有重边与自环。

输出格式

若给定的图不是弦图:

  • 输出一行 NO
  • 接下来一行,包含一个整数 $K$,表示你找到的环的环长。
  • 接下来一行,包含 $K$ 个整数 $v_0, v_1, \cdots, v_{K-1}$,描述你的环。

若给定的图是弦图:

  • 输出一行 YES
  • 接下来一行,包含 $N$ 个整数 $u_0, u_1, \cdots, u_{N-1}$,描述完美消除序列。

如果有多种合法的解,你可以输出任意一种。

样例数据

样例 1 输入

4 4
1 3
0 3
1 2
0 1

样例 1 输出

YES
2 0 1 3

样例 2 输入

5 4
0 2
1 3
0 1
3 2

样例 2 输出

NO
4
1 3 2 0

样例 3 输入

10 15
0 1
1 2
2 3
3 4
4 0
5 6
6 7
7 8
8 9
9 5
0 5
1 7
2 9
3 6
4 8

样例 3 输出

NO
5
6 3 2 9 5

子任务

对于所有数据,$1 \leq N \leq 2 \times 10^5$,$1 \leq M \leq 2 \times 10^5$,$0 \leq x,y < N$,$x \ne y$。图中没有重边与资环。

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