/*
#ifndef ONLINE_JUDGE
#include "AkbarKING.h" // aska geldi akbarking.h
#else
#define debug(...)
#define debugArr(...)
#define debugG(...)
#endif
*/
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/hash_policy.hpp>
#define int long long
#define $AzH_TxdmN$ ios_base::sync_with_stdio(0);cin.tie(nullptr);cout.tie(nullptr);
#pragma GCC target("sse,sse2,sse3,ssse3,popcnt,abm,mmx,tune=native")
#pragma GCC optimize("Ofast")
#pragma GCC optimize("no-stack-protector")
#pragma GCC optimize("unroll-loops")
#pragma GCC optimize("fast-math")
#define ep emplace_back
#define pb push_back
#define pii pair<int,int>
#define all(v) v.begin(),v.end()
#define rall(v) v.rbegin(),v.rend()
#define heap pii,vector<pii>,less<pii>
using namespace std;
using namespace __gnu_pbds;
template <typename T>
using __indexed_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
template <typename T>
using __indexed_multiset = tree<T, null_type, less_equal<T>, rb_tree_tag, tree_order_statistics_node_update>;
const int sz = 3e5+9;
const int LOG = 63;
const int MOD = 1e9+7;
const int INF = 1e18;
vector<int>v[sz];
bool used[sz];
int a[sz];
int n,k;
int res;
void dfs(int node, int par)
{
if (used[node]) return;
used[node] = 1;
vector<int>dp;
for (int to : v[node])
{
if (to != par)
{
dfs(to,node);
dp.ep(a[to]);
}
}
sort(all(dp));
for (size_t i = 0; i < dp.size(); ++i)
{
if (dp[i] + a[node] <= k) a[node] += dp[i];
else res++;
}
}
void solve()
{
cin>>n>>k;
for (int i = 1; i <= n; ++i)
{
cin>>a[i];
}
for (int i = 1,x,y; i < n; ++i)
{
cin>>x>>y;
v[x].ep(y);
v[y].ep(x);
}
dfs(1,-1);
cout<<res<<'\n';
}
signed main()
{
$AzH_TxdmN$
//freopen("paprike.in", "r", stdin);
//freopen("paprike.out", "w", stdout);
int t = 1;
//cin>>t;
while (t--)
{
solve();
}
}
