#include <bits/stdc++.h>
using namespace std;
const int MAXN = 2000 + 10;
const int MOD = (int)(1e9) + 7;
vector<int> adj[MAXN];
int a[MAXN], f[MAXN];
bool visited[MAXN];
int d, n;
void DFS(int u, int root) {
  visited[u] = true;
  f[u] = 1;
  for (int i = 0; i < adj[u].size(); i++) {
    int v = adj[u][i];
    if (!visited[v]) {
      if ((a[v] < a[root]) || (a[v] > a[root] + d)) continue;
      if ((a[v] == a[root]) && (v < root)) continue;
      DFS(v, root);
      f[u] = ((long long)(f[u]) * (f[v] + 1)) % MOD;
    }
  }
}
int main() {
  cin >> d >> n;
  for (int i = 1; i <= n; i++) cin >> a[i];
  for (int i = 1; i <= n - 1; i++) {
    int u, v;
    cin >> u >> v;
    adj[u].push_back(v);
    adj[v].push_back(u);
  }
  int result = 0;
  for (int i = 1; i <= n; i++) {
    for (int j = 1; j <= n; j++) f[j] = 0, visited[j] = false;
    DFS(i, i);
    result = (result + f[i]) % MOD;
  }
  cout << result << endl;
}
