Given a tree with $n$ vertices, each edge has a weight. Count the number of pairs of vertices $i < j$ such that the total weight on the shortest path between them does not exceed $k$.
### Input
- The first line consists of two integers $n, k$.
- The next $n - 1$ lines each contain three integers $u, v, w$, indicating an edge between vertex $u$ and $v$ with a weight of $w$.
### Output
- Output an integer representing the answer.
### Constraints
- $1 \leq n \leq 10^5$.
- $1 \leq w, k \leq 10^9$.
### Sample test
Input
```
7 10
1 6 13
6 3 9
3 5 7
4 1 3
2 4 20
4 7 2
```
Output:
```
5
```
