// Judges with GCC >= 12 only needs Ofast
// #pragma GCC optimize("O3,no-stack-protector,fast-math,unroll-loops,tree-vectorize")
// MLE optimization
// #pragma GCC optimize("conserve-stack")
// Old judges
// #pragma GCC target("sse4.2,popcnt,lzcnt,abm,mmx,fma,bmi,bmi2")
// New judges. Test with assert(__builtin_cpu_supports("avx2"));
// #pragma GCC target("avx2,popcnt,lzcnt,abm,bmi,bmi2,fma,tune=native")
// Atcoder
// #pragma GCC target("avx2,popcnt,lzcnt,abm,bmi,bmi2,fma")
/*
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
typedef tree<int,null_type,less<int>,rb_tree_tag,tree_order_statistics_node_update> ordered_set;
- insert(x)
- find_by_order(k): return iterator to the k-th smallest element
- order_of_key(x): the number of elements that are strictly smaller
*/
#include<bits/stdc++.h>
using namespace std;
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
uniform_real_distribution<> pp(0.0,1.0);
#define int long long
#define ld long double
#define pii pair<int,int>
#define piii pair<int,pii>
#define fi first
#define se second
const int inf=1e18;
const int mod=998244353;
const int maxn=200005;
const int bl=650;
const int maxs=650;
const int maxm=200005;
const int maxq=500005;
const int maxl=20;
const int maxa=1000000;
const int root=3;
int power(int a,int n){
int res=1;
while(n){
if(n&1) res=res*a%mod;
a=a*a%mod;n>>=1;
}
return res;
}
const int iroot=power(3,mod-2);
const int base=101;
namespace Tree{
vector<vector<int>> edge,Min;
vector<int> lg2,dep,L,R;
int pos;
int cmp(int u,int v){
return (dep[u]<dep[v]?u:v);
}
int lca(int u,int v){
u=L[u];v=L[v];
if(u>v) swap(u,v);
int p=lg2[v-u+1];
return cmp(Min[u][p],Min[v-(1<<p)+1][p]);
}
int dist(int u,int v){
return dep[u]+dep[v]-2*dep[lca(u,v)];
}
void dfs(int u,int p){
L[u]=++pos;Min[pos][0]=u;
dep[u]=dep[p]+1;
for(int v:edge[u]){
if(v==p) continue;
dfs(v,u);Min[++pos][0]=u;
}
R[u]=pos;
}
void init(int n){
lg2.assign(2*n+1,0);
dep.assign(n+1,0);
L.assign(n+1,0);
R.assign(n+1,0);
edge.resize(n+1);
Min.assign(2*n+1,vector<int>(maxl,0));
}
void build(int n){
init(n);
for(int i=1;i<n;i++){
int u,v;cin >> u >> v;
edge[u].push_back(v);
edge[v].push_back(u);
}
dfs(1,0);
for(int i=2;i<=pos;i++) lg2[i]=lg2[i/2]+1;
for(int i=1;i<20;i++){
for(int j=1;j<=(pos-(1<<i)+1);j++) Min[j][i]=cmp(Min[j][i-1],Min[j+(1<<(i-1))][i-1]);
}
}
}
void solve(){
int n;cin >> n;
vector<pii> p(n);
vector<int> dp(n+1,0),par(n+1),Max(n+1,0);
for(int i=1;i<=n;i++) par[i]=i;
for(int i=0;i<n;i++){cin >> p[i].fi;p[i].se=i+1;}
sort(p.begin(),p.end());Tree::build(n);
function<int(int)> findpar = [&](int u){
if(par[u]!=u) return par[u]=findpar(par[u]);
return u;
};
for(auto &[x,u]:p){
Max[u]=x;
for(int v:Tree::edge[u]){
if(Max[v]==0) continue;
v=findpar(v);par[v]=u;
dp[u]=max(dp[u],dp[v]+Tree::dist(u,v));
}
}
cout << dp[p.back().se] << '\n';
}
signed main(){
ios_base::sync_with_stdio(false);
cin.tie(NULL);cout.tie(NULL);
int test=1;//cin >> test;
while(test--) solve();
}
