#include <bits/stdc++.h> #define L(i, j, k) for(int i = (j); i <= (k); i++) #define R(i, j, k) for(int i = (j); i >= (k); i--) #define ll long long #define sz(a) ((int) a.size()) #define all(a) a.begin(), a.end() #define vi vector<int> #define pb emplace_back #define me(a, x) memset(a, x, sizeof(a)) #define fst first #define snd second #define ii pair<int, int> using namespace std; const int MAXN=2e5+5; int p[MAXN]; int n; vi adj[MAXN]; bool vis[MAXN]; pair<int,ii> getMax(int u,int d,int par){ pair<int,ii>tmp={0,{0,0}}; for(auto v:adj[u]){ if(vis[v]||v==par)continue; tmp=max(tmp,getMax(v,d+1,u)); } return max(tmp,{p[u],{u,d}}); } ll f(int u){ ll ans=0; vis[u]=true; //~ cout<<"PASO1"<<endl; for(auto v:adj[u]){ if(vis[v])continue; auto compMax=getMax(v,0,u); //~ cout<<"child="<<v<<"(MAX "<<compMax.snd.fst<<")"<<endl; //~ cout<<"PASO2"<<endl; ans=max(ans,f(compMax.snd.fst)+1ll*compMax.snd.snd+1ll); //~ cout<<"PASO3"<<endl; } return ans; } int main(){ ios::sync_with_stdio(false); cin.tie(nullptr); cin>>n; L(i,1,n){ cin>>p[i]; } L(i,0,n-2){ int a,b;cin>>a>>b; adj[a].pb(b); adj[b].pb(a); } //~ cout<<"PASS"<<endl; int init=max_element(p,p+n+1)-p; //~ cout<<init<<endl; cout<<f(init)<<endl; }