#include <bits/stdc++.h>
using namespace std;
const int N = 2005, MOD = 1e9 + 7;
int d, n, a[N], dp[N], rt;
vector<int> g[N];
void dfs(int v, int pr = -1) {
  dp[v] = 1;
  for (int to : g[v]) {
    if (to == pr) {
      continue;
    }
    if (a[to] < a[rt] || a[to] > a[rt] + d) {
      continue;
    }
    if (a[to] == a[rt] && to > rt) {
      continue;
    }
    dfs(to, v);
    dp[v] = (1ll * dp[v] * (dp[to] + 1)) % MOD;
  }
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  cin >> d >> n;
  for (int i = 1; i <= n; i++) {
    cin >> a[i];
  }
  for (int i = 1; i < n; i++) {
    int x, y;
    cin >> x >> y;
    g[x].push_back(y);
    g[y].push_back(x);
  }
  int ans = 0;
  for (int i = 1; i <= n; i++) {
    rt = i;
    dfs(rt, -1);
    ans = (ans + dp[i]) % MOD;
  }
  cout << ans;
}
