#include <bits/stdc++.h>
using namespace std;
template<typename T1, typename T2>ostream& operator<<(ostream &os, const pair<T1, T2> &p) {return os << '{' << p.first << ", " << p.second << '}';}
template<typename T_container, typename T = typename enable_if<!is_same<T_container, string>::value, typename T_container::value_type>::type> ostream& operator<<(ostream &os, const T_container &v) { os << '{'; string sep; for (const T &x : v) os << sep << x, sep = ", "; return os << '}'; }
template <typename K, typename V> ostream& operator<<(ostream& os, const map<K, V>& m) {os << "{";for (auto it = m.begin(); it != m.end(); ++it) {if (it != m.begin()) os << ", "; os << it->first << " : " << it->second;}return os << "}";}
void debug() { cerr << endl; }
template<typename Head, typename... Tail>
void debug(Head H, Tail... T) { cerr << H; debug(T...); }
#ifdef ONPC
#define deb(...) cerr << '[' << __FILE__ << ':' << __LINE__ << "] (" << #__VA_ARGS__ << "):", debug(__VA_ARGS__)
#else
#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
#define deb(...)
#endif
const int mxN = 2e5 + 5;
const int mod = 1e9 + 7;
const int dx4[] = {1, -1, 0, 0}, dy4[] = {0, 0, -1, 1};
const int dx8[] = {1, -1, 0, 0, 1, -1, 1, -1}, dy8[] = {0, 0, -1, 1, 1, -1, -1, 1};
int arr[mxN], par[mxN], cost[mxN], n, k, cnt = 0;
vector<int> g[mxN];
bool vis[mxN];
void dfs(int u) {
cost[u] += arr[u];
vis[u] = true;
int mn = INT_MAX, node = -1;
for (auto &v : g[u]) {
if (vis[v]) continue;
if (arr[v] + cost[u] <= k) {
par[v] = u;
cost[v] = cost[u];
dfs(v);
} else {
cnt++;
dfs(v);
}
}
cost[par[u]] = cost[u];
}
void run_case() {
cin >> n >> k;
for (int i = 1; i <= n; i++) cin >> arr[i], par[i] = i;
for (int i = 1, u, v; i < n; i++) {
cin >> u >> v;
g[u].push_back(v);
g[v].push_back(u);
}
// cout << "<<<<<<Output>>>>>>\n";
dfs(1);
cout << cnt << "\n";
// cout << "Cost array: ";
// for (int i = 1; i <= n; i++)
// cout << cost[i] << " ";
// cout << "\n";
// cout << "Visited array: ";
// for (int i = 1; i <= n; i++)
// cout << vis[i] << " ";
return;
}
int main() {
cin.tie(nullptr)->sync_with_stdio(false);
int test_case = 1;
// cin >> test_case;
for (int num_case = 1; num_case <= test_case; num_case++) {
run_case();
}
return 0;
}
