#include <bits/stdc++.h>
using namespace std;
long long a[500006];
long long dp[500006];
long long vis[500006];
vector<long long> v[500006];
long long on;
long long n, d, che;
void dfs(long long root, long long parent) {
  vis[root] = 1;
  dp[root] = 1;
  for (auto it : v[root]) {
    if (!vis[it]) {
      dfs(it, root);
      if (a[it] == che && it < on) {
        continue;
      }
      if (it != parent && che <= a[it] && a[it] <= che + d) {
        (dp[root] *= (1 + dp[it])) %= 1000000007;
      }
    }
  }
}
void solve() {
  cin >> d >> n;
  for (long long i = 1; i <= n; i++) cin >> a[i];
  for (long long i = 0; i < n - 1; i++) {
    long long a, b;
    cin >> a >> b;
    v[a].push_back(b);
    v[b].push_back(a);
  }
  long long ans = 0;
  for (long long i = 1; i <= n; i++) {
    on = i;
    for (long long j = 1; j <= n; j++) vis[j] = dp[j] = 0;
    che = a[i];
    dfs(i, -1);
    (ans += dp[i]) %= 1000000007;
  }
  cout << ans << "\n";
}
signed main() {
  ios_base ::sync_with_stdio(0);
  cin.tie(NULL);
  cout.tie(NULL);
  solve();
  return 0;
}
