#include <bits/stdc++.h>
#pragma GCC optimize("O3,unroll-loops")
#define pb push_back
#define F first
#define pii pair<int,int>
#define all(a) a.begin(),a.end()
#define S second
#define sz(a) (int)a.size()
#define rep(i , a , b) for(int i = (a) ; i <= (b) ; i++)
#define per(i , a , b) for(int i = (a) ; i >= (b) ; i--)
#define ld long double
#define int long long
using namespace std ;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
const int maxn = 6e6+20 , maxm = 2e4 + 220, sq = 500 , inf = 1e18+10 , mod =998244353 ;
vector <int> G[maxn] ;
int dp[maxn] ,p[maxn] , q[maxn];
void dfs(int v , int r , int mx , int d ,int pa =0 ){
if(p[v] > p[r])return ;
if(p[v] >= mx){
dp[r] = max(dp[r] , dp[v] + d);
}
for(int u : G[v]){
if(u == pa)continue ;
dfs(u , r , max(mx , p[u]) , d+1 , v);
}
}
vector <int> u[maxn] ;
signed main(){
ios_base::sync_with_stdio(false) ; cin.tie(0) ;
int n ;
cin >> n ;
rep(i ,1, n){
cin >> p[i] ;
q[p[i]]= i ;
}
rep(i , 1, n-1){
int v, u ;
cin >> v >> u ;
G[v].pb(u);
G[u].pb(v) ;
}
if(n <= 5000){
rep(i ,1, n){
dfs(q[i] , q[i] , 0 , 0) ;
}
cout << dp[q[n]] << "\n";
exit(0) ;
}
vector <int> vec ;
per(i , n , 1){
while(sz(vec) && p[vec.back()] < p[i]){
u[i].pb(vec.back()) ;vec.pop_back() ;
}
vec.pb(i) ;
}
vec.clear();
rep(i ,1 ,n){
while(sz(vec) && p[vec.back()] < p[i]){
u[i].pb(vec.back()) ;vec.pop_back() ;
}
vec.pb(i) ;
}
rep(i ,1, n){
for(int u : u[q[i]]){
dp[q[i]] = max(dp[q[i]] , dp[u] + abs(u - q[i])) ;
}
}
cout << dp[q[n]] << "\n";
}
/*
*/
