7633: [CSES Problem Set] Fixed-Length Paths II
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Description
Given a tree of $n$ nodes, your task is to count the number of distinct paths that have at least $k_1$ and at most $k_2$ edges.
Input
The first input line contains three integers $n, k_1, k_2$: the number of nodes and the path lengths. The nodes are numbered $1,2,\ldots,n$.
Then there are $n-1$ lines describing the edges. Each line contains two integers $a$ and $b$: there is an edge between nodes $a$ and $b$.
Then there are $n-1$ lines describing the edges. Each line contains two integers $a$ and $b$: there is an edge between nodes $a$ and $b$.
Output
Print one integer: the number of paths.
Constraints
$1≤k1≤k2≤n≤2⋅10^5$
$1 \le a,b \le n$
$1 \le a,b \le n$
Sample 1 Input
5 2 3
1 2
2 3
3 4
3 5
Sample 1 Output
6