#include <bits/stdc++.h>
using namespace std;
long long int a[100001] = {0};
long long int d[100001] = {0};
long long int vis[100001] = {0};
long long int cons[100001] = {0};
vector<long long int> vec[100001];
void dfs(long long int x, long long int p) {
  vis[x] = 1;
  if (a[x] == 1) {
    if (a[p] == 1) {
      cons[x] = cons[p] + 1;
    } else {
      cons[x] = 1;
    }
    d[x] = max(d[p], cons[x]);
  } else {
    cons[x] = 0;
    d[x] = d[p];
  }
  for (long long int i = 0; i < vec[x].size(); i++) {
    if (vis[vec[x][i]] == 1)
      continue;
    else {
      dfs(vec[x][i], x);
    }
  }
}
signed main() {
  long long int n, m;
  cin >> n >> m;
  for (long long int i = 0; i < n; i++) cin >> a[i + 1];
  for (long long int i = 0; i < n - 1; i++) {
    long long int x, y;
    cin >> x >> y;
    vec[x].push_back(y);
    vec[y].push_back(x);
  }
  dfs(1, 0);
  long long int count = 0;
  for (long long int i = 2; i <= n; i++) {
    if (vec[i].size() == 1 && d[i] <= m) count++;
  }
  cout << count;
}
