Problem A
Cities

In a far away kingdom, there are $N$ cities numbered between $0$ and $N - 1$. The cities are connected by $N - 1$ two-way roads. Each road has the same length, and connects exactly two cities, such that there is a unique path between any pair of cities.

For any two cities $A$ and $B$, denote by $L(A, B)$ the number of roads of this unique path between cities $A$ and $B$. Given an integer $K$, for how many pairs of cities $A, B$ is $L(A, B) = K$?

Input

The first line contains the integers $N$ and $K$ ($1 \le K \le N \le 100\, 000$), described in the statement.

The two lines contains the $N - 1$ integers $f_1, \dots , f_{N-1}$ ($0 \le f_ i < N$) and the $N - 1$ integers $t_1, \dots , t_{N-1}$ ($0 \le t_ i < N$) respectively. These describe the roads of the city: there is a road between city $f_ i$ and $t_ i$ for each $i$.

Output

Output the number of pairs of cities that have exactly $K$ roads between them.

Scoring

Your solution will be tested on a set of test groups, each worth a number of points. To get the points for a test group you need to solve all test cases in the test group.

Explanation of sample 1

Let the kingdom have $N = 5$ cities, connected by roads as in the figure below:

Figure 1: Illustration of the example

The following 4 pairs have a single road between them: $(0, 1), (0, 2), (0, 4), (3, 4)$.

The following 4 pairs have two roads between them: $(0, 3), (1, 2), (1, 4), (2, 4)$.

The following 2 pairs have three roads between them: $(1, 3), (2, 3)$.

This means that if for $K = 1, 2, 3$, the answers would be $4, 4, 2$ respectively.

5 2
0 0 0 3
1 2 4 4

4