#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define ull unsigned long long
#define pb(e) push_back(e)
#define sv(a) sort(a.begin(),a.end())
#define sa(a,n) sort(a,a+n)
#define mp(a,b) make_pair(a,b)
#define vf first
#define vs second
#define ar array
#define all(x) x.begin(),x.end()
const int inf = 0x3f3f3f3f;
const int mod = 1000000007;
const double PI=3.14159265358979323846264338327950288419716939937510582097494459230;
mt19937_64 RNG(chrono::steady_clock::now().time_since_epoch().count());
bool remender(ll a , ll b){return a%b;}
const int N = 200003 , L = 20;
struct dsu {
vector<int> p , siz , mn;
void init(vector<int> a){
int n = a.size();
p.resize(n);
siz.resize(n);
mn.resize(n);
for(int i = 0; i < n; i++){
p[i] = i;
siz[i] = 1;
mn[i] = a[i];
}
}
int get(int x){
return p[x] = (p[x] == x ? x : get(p[x]));
}
void unio(int x , int y){
x = get(x);
y = get(y);
if(x == y)return;
if(siz[x] > siz[y]){
swap(x,y);
}
p[x] = y;
siz[y] += siz[x];
mn[y] = max(mn[y],mn[x]);
}
};
vector<int> adj[N];
int timer,tin[N],tout[N],up[N][L],depth[N];
void dfs(int node , int par){
tin[node] = timer++;
up[node][0] = par;
for(int i = 1; i < L; i++){
up[node][i] = up[up[node][i-1]][i-1];
}
for(int i : adj[node]){
if(i!=par){
depth[i] = depth[node] + 1;
dfs(i,node);
}
}
tout[node] = timer++;
}
bool is_lca(int x , int y){
return tin[x] <= tin[y] && tout[x] >= tout[y];
}
int find(int x , int y){
if(is_lca(x,y))return x;
if(is_lca(y,x))return y;
for(int i = L-1; i >= 0; i--){
if(!is_lca(up[x][i],y))x = up[x][i];
}
return up[x][0];
}
int dis(int u , int v){
int lca = find(u , v);
return depth[u] + depth[v] - 2 * depth[lca];
}
void solve(){
int n;
cin >> n;
vector<int> arr(n + 1);
arr[0] = 0;
int pos[n + 1];
for(int i = 1; i <= n; i++){
cin >> arr[i];
pos[arr[i]] = i;
}
for(int i = 0; i < n - 1; i++){
int u , v;
cin >> u >> v;
adj[u].pb(v);
adj[v].pb(u);
}
timer = 0;
depth[1] = 0;
dfs(1,1);
dsu d;
d.init(arr);
ll ans[n + 1];
ans[1] = 0;
for(int i = 2; i <= n; i++){
ans[i] = 0;
int node = pos[i];
for(int j : adj[node]){
if(arr[j] < i){
//cout << dis(node , pos[d.mn[d.get(j)]]) << ' ' << pos[d.mn[d.get(j)]] << ' ';
//cout << dis(node,d.mn[d.get(j)]) << ' ' << d.mn[d.get(j)] << ' ';
ans[i] = max(ans[i] , dis(node,pos[d.mn[d.get(j)]]) + ans[d.mn[d.get(j)]]);
d.unio(j , node);
}
}
//cout << ans[i] << ' ';
}
cout << ans[n] << '\n';
}
int main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
//freopen("deleg.in", "r", stdin);
//freopen("deleg.out", "w", stdout);
//int t;cin >> t;while(t--)
solve();
return 0;
}
