#include<bits/stdc++.h>
using namespace std;
const int N = 20000;
int head[N], idx;
int n, f[N];
bool vis[N];
struct tTree{
	int to, pre;
} edge[N];

void ade(int,int);
void dfs(int);

int main(){
	cin >> n;
	for (int i = 1; i <= n; ++i)
		cin >> f[i];
	for (int i = 1; i <= n-1; ++i){
		int a, b;
		cin >> a >> b;
		ade(a,b); ade(b,a);
	}
	dfs(1);
	int ans = 0xafafafaf;
	for (int i = 1; i <= n; ++i)
		ans = max(ans,f[i]);
	cout << ans;
	return 0;
}
void ade(int u, int v){
	edge[++idx].pre = head[u];
	edge[idx].to = v;
	head[u] = idx;
} 
void dfs(int u){
	vis[u] = true;
	for (int i = head[u]; i; i = edge[i].pre){
		int v = edge[i].to;
		if (!vis[v]){
			dfs(v);
			f[u] = max(f[u],f[u]+f[v]);
		}
	}
}