#include <bits/stdc++.h>
using namespace std;
void __print(int x) { cerr << x; }
void __print(long x) { cerr << x; }
void __print(long long x) { cerr << x; }
void __print(unsigned x) { cerr << x; }
void __print(unsigned long x) { cerr << x; }
void __print(unsigned long long x) { cerr << x; }
void __print(float x) { cerr << x; }
void __print(double x) { cerr << x; }
void __print(long double x) { cerr << x; }
void __print(char x) { cerr << '\'' << x << '\''; }
void __print(const char *x) { cerr << '\"' << x << '\"'; }
void __print(const string &x) { cerr << '\"' << x << '\"'; }
void __print(bool x) { cerr << (x ? "true" : "false"); }
template <typename T, typename V>
void __print(const pair<T, V> &x) {
  cerr << '{';
  __print(x.first);
  cerr << ',';
  __print(x.second);
  cerr << '}';
}
template <typename T>
void __print(const T &x) {
  int f = 0;
  cerr << '{';
  for (auto &i : x) cerr << (f++ ? "," : ""), __print(i);
  cerr << "}";
}
void _print() { cerr << "]\n"; }
template <typename T, typename... V>
void _print(T t, V... v) {
  __print(t);
  if (sizeof...(v)) cerr << ", ";
  _print(v...);
}
template <typename T>
void printVec(const T &v, char sep = ' ') {
  for (auto &i : v) cout << i << sep;
}
template <typename T>
void printVecPair(const T &v, char sep = ' ') {
  for (auto &i : v) cout << i.first << " " << i.second << sep;
}
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int n, m;
  cin >> n >> m;
  vector<int> cats(n);
  for (int &i : cats) cin >> i;
  vector<int> g[n];
  int ed = n - 1;
  while (ed--) {
    int v, u;
    cin >> v >> u;
    v--;
    u--;
    g[v].push_back(u);
    g[u].push_back(v);
  }
  queue<int> q;
  q.push(0);
  vector<int> dis(n, 0);
  dis[0] = cats[0];
  vector<bool> visited(n, 0);
  int ans = 0;
  while (!q.empty()) {
    int p = q.front();
    q.pop();
    visited[p] = true;
    for (int child : g[p]) {
      if (visited[child]) continue;
      dis[child] = cats[child] * dis[p] + cats[child];
      ;
      if (dis[child] <= m) {
        q.push(child);
        if (g[child].size() == 1 && child != 0) ans++;
      }
    }
  }
  cout << ans;
  return 0;
}
