Kefa and Park

#include <bits/stdc++.h>
using namespace std;

int n, m;
vector<vector<int>> gr;
vector<int> c;

int solve(int u, int cnt, int par) {
  if (cnt > m) return 0;
  int subtr_count = (gr[u].size() == 1 and par == gr[u][0] ? 1 : 0);
  for (int to : gr[u]) if (to != par) {
    subtr_count += solve(to, (c[to] ? cnt + c[to] : 0), u);
  }
  return subtr_count;
}

int main() {
  cin.tie(0)->sync_with_stdio(0);

  cin >> n >> m;

  gr.assign(n, vector<int>());
  c.assign(n, -1);

  for (int i = 0; i < n; ++i) {
    cin >> c[i];
  }

  for (int i = 0; i < n-1; ++i) {
    int a, b; cin >> a >> b, --a, --b;
    gr[a].push_back(b);
    gr[b].push_back(a);
  }

  cout << solve(0, c[0], -1) << '\n';
}