/// designed by Oruc Cabbarli
#pragma GCC optimize("O3")
#include <bits/stdc++.h>
using namespace std;
#define int long long
#define vi vector<int>
#define pii pair<int,int>
#define vpii vector<pii>
#define fi first
#define se second
#define pb push_back
#define all(v) v.begin(), v.end()
#define endl '\n'
template<typename T>void show(vector<T> &v){
for(auto &i: v){
cout << i << ' ';
}
cout << endl;
}
const int N = 1e3+5;
const int INF = 1e18;
const int LOG = 20;
const int MOD = 1e9+7;
int n,k,c=0;
int a[N];
vi g[N],dp(N);
void dfs(int v , int p){
vi tmp;
for(auto &u: g[v]){
if(u == p) {
continue;
}
dfs(u,v);
tmp.pb(a[u]);
dp[v] += dp[u];
}
sort(tmp.begin(), tmp.end());
for(int i = 0; i < tmp.size(); i++){
if(a[v]+tmp[i] <= k){
a[v]+=tmp[i];
}
else{
dp[v]++;
}
}
}
void solve(){
cin >> n >> k;
for(int i = 1; i <= n; i++){
cin >> a[i];
}
for(int i = 1; i < n; i++){
int v,u;
cin >> v >> u;
g[u].pb(v);
g[v].pb(u);
}
dfs(1,0);
cout << dp[1] << endl;
}
signed main(){
ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
int t = 1;
//cin >> t;
for(int i = 1; i <= t; i++){
//cout << "Case #" << i << ": ";
solve();
}
}
