Problem:
You have a Tree with N nodes rooted at 1 where $i^{th}$ node is associated with a value $A_i$. Now consider the following definition:
K-Tuple: A tuple of $K+1$ nodes $(X_{1},X_{2},X_{3},\dots,X_{K+1})$ is a K-Tuple if:
1.) $X_{i}$ is an ancestor of $X_{i+1} \forall 1 \leq i \leq K$
2.) $A_{X_{i}} > A_{X_{i+1}} \forall 1 \leq i \leq K$

Calculate the number of K-Tuples in the tree.

Input:
First line contains two integers N and K, the number of nodes in the tree and the value for the Tuple type you need to calculate answer for.
Next line contains N space separated integers where the $i^{th}$ integer denotes the value $A_i$.
Next $N-1$ lines contains X and Y denoting that there is an edge between them.

Output:
Output a single integer mod $(10^9+7)$ denoting the number of K-tuples in the tree.

Constraints:
$1 ≤ N,A_i ≤ 100000$
$1 ≤ X,Y ≤ N$
$1 ≤ K ≤ 20$