#include<bits/stdc++.h>
using namespace std;
long long n,k;
long long h[100100];
vector <long long> g[100100];
pair <long long,long long> dp[100100];
void dfs(long long u,long long pre){
for (auto v:g[u]){
if (v == pre)continue;
dfs(v,u);
}
dp[u] = {0,h[u]};
vector <long long> all;
for (auto v:g[u]){
if (v == pre)continue;
dp[u].first += dp[v].first;
dp[u].second += dp[v].second;
all.push_back(dp[v].second);
}
sort(all.begin(),all.end(),greater <long long> ());
long long cur = 0;
while (dp[u].second > k){
dp[u].second -= all[cur];
cur++;
dp[u].first++;
}
}
int main(){
ios_base::sync_with_stdio(0);cin.tie(nullptr);cout.tie(nullptr);
cin>>n>>k;
for (long long i = 1;i <= n;i ++){
cin>>h[i];
}
for (long long i = 1;i < n;i ++){
long long x,y;
cin>>x>>y;
g[x].push_back(y);
g[y].push_back(x);
}
dfs(1,1);
cout<<dp[1].first<<'\n';
return 0;
}
