//----------vahagng----------//
#define _CRT_SECURE_NO_WARNINGS
#include <bits/stdc++.h>
// #include <ext/pb_ds/assoc_container.hpp>
using namespace std;
// using namespace __gnu_pbds;
// template <class T> using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
#ifndef ONLINE_JUDGE
#define dbg(x) cerr << #x <<" "; print(x); cerr << endl;
#else
#define dbg(x)
#endif
void print(long long t) { cerr << t; }
void print(int t) { cerr << t; }
void print(string t) { cerr << t; }
void print(char t) { cerr << t; }
void print(double t) { cerr << t; }
void print(long double t) { cerr << t; }
void print(unsigned long long t) { cerr << t; }
template <class T, class V> void print(pair <T, V> p);
template <class T> void print(vector <T> v);
template <class T> void print(set <T> v);
template <class T, class V> void print(map <T, V> v);
template <class T> void print(multiset <T> v);
template <class T, class V> void print(T v[], V n) { cerr << "["; for (int i = 0; i < n; i++) { cerr << v[i] << " "; } cerr << "]"; }
template <class T, class V> void print(pair <T, V> p) { cerr << "{"; print(p.first); cerr << ","; print(p.second); cerr << "}"; }
template <class T> void print(vector <T> v) { cerr << "[ "; for (T i : v) { print(i); cerr << " "; } cerr << "]"; }
template <class T> void print(set <T> v) { cerr << "[ "; for (T i : v) { print(i); cerr << " "; } cerr << "]"; }
template <class T> void print(unordered_set <T> v) { cerr << "[ "; for (T i : v) { print(i); cerr << " "; } cerr << "]"; }
template <class T> void print(multiset <T> v) { cerr << "[ "; for (T i : v) { print(i); cerr << " "; } cerr << "]"; }
template <class T, class V> void print(map <T, V> v) { cerr << "[ "; for (auto i : v) { print(i); cerr << " "; } cerr << "]"; }
#define ll long long
#define all(v) v.begin(), v.end()
#define rall(v) v.rbegin(), v.rend()
#define ld long double
#define sz(v) v.size()
#define endl '\n'
const ll inf = 2e18, mod = 1e9 + 7, mod2 = 998244353;
void SetIO(string str = "") {
if (str != "") {
freopen((str + ".in").c_str(), "r", stdin);
freopen((str + ".out").c_str(), "w", stdout);
}
else {
freopen("input.txt", "r", stdin);
freopen("output.txt", "w", stdout);
}
}
void FastIO() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
cout.tie(nullptr);
}
const int N = 1e6 + 10, M = 2e7 + 10;
mt19937 rnd(chrono::system_clock::now().time_since_epoch().count());
ll binpow(ll a, ll b, ll m) {
ll res = 1;
while (b) {
if (b & 1) {
res = (res * a) % m;
}
b >>= 1;
a = (a * a) % m;
}
return res;
}
__int128_t gcd(__int128_t a, __int128_t b) {
while (b) {
a %= b;
swap(a, b);
}
return a;
}
__int128_t lcm(__int128_t a, __int128_t b) {
return a / gcd(a, b) * b;
}
ll n, k, dp[N], ans, a[N], sum[N], sum_dp[N];
vector<int>adj[N];
void dfs0(int node, int parent) {
sum[node] = a[node];
for(auto i : adj[node]){
if (i == parent) continue;
dfs0(i, node);
sum[node] += sum[i];
}
}
void dfs(int node, int parent) {
sum_dp[node] = a[node];
vector<ll> V;
for (auto i : adj[node]) {
if (i == parent) continue;
dfs(i, node);
dp[node] += dp[i];
V.push_back(sum_dp[i]);
}
sort(all(V));
int c = 0;
for (auto i : V) {
if (sum_dp[node] + i <= k) {
sum_dp[node] += i;
c++;
}
}
dp[node] += V.size() - c;
}
void reroot(int node, int parent, int grand_parent) {
if (node == 1) {
for (auto i : adj[node]) {
reroot(i, node, parent);
}
return;
}
dp[parent] -= dp[node];
dp[node] += dp[parent];
vector<ll> V;
for (auto i : adj[parent]) {
if (i == grand_parent) continue;
V.push_back(sum_dp[i]);
}
sort(all(V));
ll S = sum_dp[parent];
int it = 0;
while (it < V.size() && S != a[parent]) {
S -= sum_dp[it];
if (sum_dp[it] == node) {
sum_dp[parent] -= sum_dp[node];
dp[parent]--;
break;
}
it++;
}
for (auto i : adj[node]) {
if (i == parent) continue;
V.push_back(sum_dp[i]);
}
sort(all(V));
int itr = 0;
while (itr < V.size() && sum_dp[node] != a[node]) {
sum_dp[node] -= V[itr++];
}
V.clear();
for (auto i : adj[node]) {
V.push_back(sum_dp[i]);
}
sort(all(V));
int c = 0;
for (auto i : V) {
if (sum_dp[node] + i <= k) {
sum_dp[node] += i;
c++;
}
}
dp[node] += V.size() - c;
ans = min(ans, dp[node]);
for (auto i : adj[node]) {
if (i == parent) continue;
reroot(i, node, parent);
}
}
void solve(int tc) {
cin >> n >> k;
for(int i = 1; i <= n; i++){
cin >> a[i];
}
for (int i = 1; i < n; i++) {
int u, v;
cin >> u >> v;
adj[u].push_back(v);
adj[v].push_back(u);
}
dfs0(1, 0);
dfs(1, 0);
ans = dp[1];
reroot(1, 0, 0);
cout << ans << endl;
}
void precalc() {
}
int main() {
// SetIO("teamwork");
FastIO();
int test_case = 1;
// cin >> test_case;
precalc();
int cnt = 1;
while (test_case--) {
solve(cnt++);
}
return 0;
}
