#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 n, k, cost[mxN], ans = 0;
vector<int> g[mxN];
void dfs(int u, int p) {
    vector<int> vec;
    for (auto &v : g[u]) {
        if (v == p) continue;
        dfs(v, u);
        vec.push_back(cost[v]);
    }
    sort(vec.begin(), vec.end());
    for (auto &i : vec) {
        if (cost[u] + i <= k)   cost[u] += i;
        else                    ans++;
    }
}
void run_case() {
    cin >> n >> k;
    for (int i = 1; i <= n; i++)    cin >> cost[i];
    for (int i = 1, u, v; i < n; i++) {
        cin >> u >> v;
        g[u].push_back(v);
        g[v].push_back(u);
    }
    dfs(1, 1);
    cout << ans;
    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;
}
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