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Time Limit: 1.0 s Memory Limit: 512 MB Total points: 100 Hackable ✓

#12819. 匹配

Statistics

Yuta 有一个包含 $n$ 个节点和 $n-1$ 条边的无向连通图 $G = \langle V, E \rangle$。Yuta 可以选择 $E$ 的某个子集并将它们删除。显然,Yuta 有 $2^{n-1}$ 种不同的删除方案。

现在,Yuta 想知道有多少种删除边的方案,使得剩余图 $G'$ 的最大匹配大小能被 $m$ 整除。由于答案可能非常大,请输出其对 $998\,244\,353$ 取模的结果。

边集 $S$ 是图 $G = \langle V, E \rangle$ 的一个匹配,当且仅当 $V$ 中的每个节点在 $S$ 中至多连接一条边。图 $G$ 的最大匹配定义为 $G$ 中规模最大的匹配。

输入格式

第一行包含两个整数 $n$ 和 $m$ ($1 \le n \le 5 \cdot 10^4, 1 \le m \le 200$)。

接下来 $n-1$ 行,每行包含两个整数 $u$ 和 $v$,描述 $G$ 中的一条边。

输出格式

输出一行,包含一个整数:答案对 $998\,244\,353$ 取模的结果。

样例

样例输入 1

4 2
1 2
2 3
3 4

样例输出 1

3

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