#include<bits/stdc++.h>
#define N 200010
#define LOGN 20
#define int long long
using namespace std;
struct DSU{
int pai[N];
DSU(){
for(int i = 0;i < N;i++){
pai[i] = i;
}
}
int find(int x){
return (x == pai[x] ? x : find(pai[x]));
}
void join(int a, int b){
b = find(b);
pai[b] = a;
return;
}
} dsu;
int n;
int p[N];
vector <pair <int,int>> ord;
vector <int> g[N];
int dp[N];
int h[N], pai[N][LOGN];
void dfs(int v, int p){
pai[v][0] = p;
for(auto x : g[v]){
if(x == p) continue;
h[x] = h[v]+1;
dfs(x, v);
}
return;
}
int query(int x, int y){
if(h[x] > h[y]) swap(x, y);
int t = h[y] - h[x];
int res = 0;
for(int i = 0;i < LOGN;i++){
if((t & (1 << i))){
int pp = (1 << i);
res += pp;
y = pai[y][i];
}
}
if(x == y) return res;
for(int i = LOGN-1;i >= 0;i--){
if(pai[x][i] != pai[y][i]){
x = pai[x][i];
y = pai[y][i];
int pp = (1 << i);
res += 2*pp;
}
}
return res+2;
}
int32_t main(){
cin >> n;
for(int i = 1;i <= n;i++){
int x;
cin >> x;
p[i] = x;
ord.push_back({x, i});
}
sort(ord.begin(), ord.end());
for(int i = 1;i < n;i++){
int a, b;
cin >> a >> b;
g[a].push_back(b);
g[b].push_back(a);
}
dfs(1, 1);
for(int i = 1;i < LOGN;i++){
for(int v = 1;v <= n;v++){
pai[v][i] = pai[pai[v][i-1]][i-1];
}
}
for(auto aa : ord){
int v = aa.second;
for(auto x : g[v]){
if(p[x] > p[v]) continue;
int t = dsu.find(x);
dp[p[v]] = max(dp[p[v]], dp[p[t]] + query(v, t));
dsu.join(v, t);
}
}
cout << dp[n] << endl;
}
