#include<cstdio>
#include<cstring>
#include<iostream>
#include<cstdlib>
#include<algorithm>
#include<vector>
using namespace std;

const int maxn=500010;
int n,cnt,u,v;
int h[maxn];
struct edge{
	int to,next;
}G[maxn<<1];
int d[maxn],f[maxn],c[maxn];
vector<int>son[maxn];
bool cmp(const int &a,const int &b){
	return max(f[a],d[a]+2+f[b])<max(f[b],d[b]+2+f[a]);
}
void read(int &num){
	num=0;char ch=getchar();
	while(ch<'!')ch=getchar();
	while(ch>='0'&&ch<='9')num=num*10+ch-'0',ch=getchar();
}
void add(int x,int y){++cnt;G[cnt].to=y;G[cnt].next=h[x];h[x]=cnt;}
void DFS(int u,int fa){
	for(int i=h[u];i;i=G[i].next){
		int v=G[i].to;
		if(v==fa)continue;
		son[u].push_back(v);
		DFS(v,u);
		d[u]=d[u]+d[v]+2;
	}
	int sz=son[u].size();
	if(!sz){d[u]=0;f[u]=c[u];return;}
	sort(son[u].begin(),son[u].end(),cmp);
	int sum=0;
	for(int i=0;i<sz;++i){
		f[u]=max(f[u],sum+f[son[u][i]]+1);
		sum+=d[son[u][i]]+2;
	}f[u]=max(f[u],c[u]);
}
int main(){
	freopen("gamebeta.in","r",stdin);
	freopen("gamebeta.out","w",stdout);
	read(n);
	for(int i=1;i<=n;++i)read(c[i]);
	for(int i=1;i<n;++i){
		read(u);read(v);
		add(u,v);add(v,u);
	}
	DFS(1,-1);
	printf("%d\n",max(f[1],d[1]+c[1]));
	return 0;
}