/*
Language: c++
Author: lxtgogogo
Date: 2016.04.15
*/
#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<cmath>
#include<iomanip>
#include<queue>
using namespace std;
inline int read(){
	int x=0;bool f=true;char ch=getchar();
	while(ch>'9' || ch<'0')	{if(ch=='-'){f=false;}ch=getchar();}
	while(ch>='0' && ch<='9')	{x=(x<<1)+(x<<3)+ch-'0';ch=getchar();}
	return f?x:-x;
}
priority_queue< int,vector< int >,less< int > > big;
//q.push();
//q.top();
const int r=500010;
int n=0,ans=0;
int hash[r]={},ge=0;
int w[r]={};
int du[r]={},when[r]={},size[r]={},fa[r]={};
int bian[50001][100]={};

struct GTMD{
	int v,id;
}p[r];
struct hehe{
	int y,next;
}e[r*2];
int linkk[r]={},len=0;

bool mycmp(GTMD a,GTMD b){return a.v<b.v;}
bool mycmp2(GTMD a,GTMD b){return a.id<b.id;}
inline void insert(int a,int b){
	e[++len].next=linkk[a];linkk[a]=len;e[len].y=b;
}
void init(){
	n=read();
	for(int i=1;i<=n;i++)	{p[i].v=read();p[i].id=i;}
	for(int i=1;i<n;i++)
	{
		int x=read(),y=read();
		insert(x,y);
		insert(y,x);
	}
	sort(p+1,p+n+1,mycmp);
	for(int i=1;i<=n;i++)
	{
		w[p[i].id]=++ge;
		hash[ge]=p[i].id;
	}
	sort(p+1,p+n+1,mycmp2);
}
void dfs(int k){//计算每个点的出度
	size[k]=1;
	for(int i=linkk[k];i;i=e[i].next)
		if(e[i].y!=fa[k])
		{
			du[k]++;
			fa[e[i].y]=k;
			dfs(e[i].y);
			size[k]+=size[e[i].y];
		}
}
void top_sort(){
	for(int i=1;i<=n;i++)
		if(du[i]==0)	big.push(w[i]);
	int sig=0;
	while(sig<n)
	{
		int t=big.top();
		t=hash[t];
		big.pop();
		sig++;
		bian[fa[t]][++bian[fa[t]][0]]=t;
		for(int i=linkk[t];i;i=e[i].next)
			if(du[e[i].y]>0)
			{
				du[e[i].y]--;
				if(du[e[i].y]==0)	big.push(w[e[i].y]);
			}
	}
}
void countans(int k,int ti,int fa){
	if(ti+p[k].v>ans)	ans=ti+p[k].v;
	for(int i=1;i<=bian[k][0];i++)
	{
		countans(bian[k][i],ti+1,k);
		ti+=size[bian[k][i]]*2;
	}
	if(k==1)	ans=max(ans,ti+p[1].v);
}
void work1(){
	dfs(1);
	top_sort();
	countans(1,0,0);
	printf("%d\n",ans);
}
void work2(){
	cout<<size[1]*2-2+p[1].v<<endl;
}
int main(){
	freopen("gamebeta.in","r",stdin);
	freopen("gamebeta.out","w",stdout);
	
	init();
	if(n<=50000)	work1();
	else	work2();
	
	fclose(stdin);fclose(stdout);
	return 0;
}