#include <bits/stdc++.h>
using namespace std;
const int MOD = 1e9 + 7;
const int MAXN = 2e3 + 5;
long long dp[MAXN];
vector<int> adj[MAXN];
int ar[MAXN];
int src;
int d;
bool done[MAXN][MAXN];
void DFS(int s, int par = -1) {
  dp[s] = 1;
  for (auto it : adj[s]) {
    if (it == par) continue;
    if (ar[it] < ar[src]) continue;
    if (ar[it] - ar[src] > d) continue;
    if (done[it][src]) continue;
    done[it][src] = done[src][it] = true;
    DFS(it, s);
    dp[s] *= 1LL + dp[it];
    if (dp[s] >= MOD) dp[s] %= MOD;
  }
}
int main() {
  int n;
  cin >> d >> n;
  for (int i = 1; i <= n; i++) {
    scanf("%d", &ar[i]);
  }
  for (int i = 1; i < n; i++) {
    int u, v;
    scanf("%d%d", &u, &v);
    adj[u].push_back(v);
    adj[v].push_back(u);
  }
  long long ans = 0;
  for (int i = 1; i <= n; i++) {
    src = i;
    DFS(i);
    ans += dp[i];
    if (ans >= MOD) ans %= MOD;
  }
  cout << ans << endl;
  return 0;
}
