#include<bits/stdc++.h>
using namespace std;
#define int long long
const int maxn = 2e5 + 5;
vector<pair<int, int>> g[maxn];
vector<int> adj[maxn];
int up[maxn][18], pos[maxn], dp[maxn], h[maxn], p[maxn], a[maxn];
int lca(int u, int v){
if(h[u] < h[v]) swap(u, v);
int k = h[u] - h[v];
for(int i = 0; i <= 17; i++){
if(k & (1 << i)) u = up[u][i];
}
if(u == v) return u;
for(int i = 17; i >= 0; i--){
if(up[u][i] != up[v][i]){
u = up[u][i];
v = up[v][i];
}
}
return up[u][0];
}
void calc(int u){
for(auto [v, w]: g[u]){
calc(v);
dp[u] = max(dp[u], dp[v] + w);
}
}
void dfs(int u, int pre){
for(int v: adj[u]){
if(v == pre) continue;
h[v] = h[u] + 1;
up[v][0] = u;
dfs(v, u);
}
}
int find(int u){
return (p[u] == u ? u : p[u] = find(p[u]));
}
void merge(int u, int v){
u = find(u), v = find(v);
if(a[u] < a[v]) swap(u, v);
p[v] = u;
}
signed main(){
ios_base::sync_with_stdio(false);
cin.tie(0); cout.tie(0);
int n; cin >> n;
for(int i = 1; i <= n; i++){
cin >> a[i];
pos[a[i]] = i;
p[i] = i;
}
for(int i = 1; i <= n - 1; i++){
int u, v; cin >> u >> v;
adj[u].push_back(v);
adj[v].push_back(u);
}
dfs(1, -1);
for(int j = 1; j <= 17; j++){
for(int i = 1; i <= n; i++) up[i][j] = up[up[i][j - 1]][j - 1];
}
for(int i = 1; i <= n; i++){
int u = pos[i];
for(auto v: adj[u]){
if(a[v] < a[u]){
v = find(v);
merge(u, v);
g[u].push_back({v, h[u] + h[v] - 2 * h[lca(u, v)]});
}
}
}
calc(pos[n]);
cout << dp[pos[n]];
}
