/*
Editor: Abdelrahman Hossam
Nickname: Blobo2_Blobo2
IOI next year isA :)
*/
/*#pragma GCC optimize("Ofast,no-stack-protector,unroll-loops,fast-math,O3")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,sse4.2,popcnt,abm,mmx,avx2,tune=native")
#pragma GCC optimize("-ffast-math")
#pragma GCC optimize("-funroll-loops")
#pragma GCC optimize("-funroll-all-loops,-fpeel-loops,-funswitch-loops")*/
#include<bits/stdc++.h>
using namespace std;
#define int long long
#define endl "\n"
#define all(v) v.begin(),v.end()
#define gen(arr,n,nxt) generate(arr,arr+n,nxt)
#define Blobo2_el_7akim_elly_3ayz_yro7_IOI_w_3ayz_yakol_jilaty ios_base::sync_with_stdio(false);cin.tie(0);
#define EPS 0.00000001
const int mo=1e9+7,INF=1e18;
int nxt(){int x;cin>>x;return x;}
int n,k;
vector<int>adj[100001];
int val[100001];
int cnt=0;
void dfs(int u =0,int par =-1){
if(adj[u].size() == 0)
return;
for(auto v:adj[u])
if(v!=par)
dfs(v,u);
vector<int>v2;
for(auto v:adj[u])
if(v!=par)
v2.push_back(val[v]);
sort(all(v2));
for(int i=0;i<v2.size();i++){
if(val[u]+v2[i] <= k)
val[u] += v2[i];
else
cnt++;
}
return;
}
signed main(){
Blobo2_el_7akim_elly_3ayz_yro7_IOI_w_3ayz_yakol_jilaty
n=nxt(),k=nxt();
gen(val,n,nxt);
for(int i=0;i<n-1;i++){
int x= nxt()-1,y=nxt()-1;
adj[x].push_back(y);
adj[y].push_back(x);
}
dfs();
cout<<cnt;
return 0;
}
