#include "bits/stdc++.h"
using namespace std;
#define ll long long
#define ln '\n'
const int N = 2e5 + 5;
const int LG = 20;
int n, glit = 1, root, p[N], mx[LG][N], up[LG][N], where[N], sz[N];
vector<int> adj[N];
int dfs(int u, int par){
up[0][u] = par;
mx[0][glit] = u;
where[u] = glit;
glit++;
int tot = 1;
for (auto v: adj[u]){
if (v == par) continue;
tot += dfs(v, u);
}
sz[where[u]] = tot;
return tot;
}
int answer(int l, int r){
if (l > r) return 0;
int lg = log2(r-l+1);
return p[mx[lg][l]] > p[mx[lg][r-(1<<lg)+1]]? mx[lg][l]: mx[lg][r-(1<<lg)+1];
}
bool is_ancestor(int u, int v){
return where[u] <= where[v] && where[v] <= where[u] + sz[where[u]] - 1;
}
int lca(int u, int v){
if (is_ancestor(u, v)) return u;
if (is_ancestor(v, u)) return v;
for (int i = LG-1; i >= 0; i--){
if (!is_ancestor(up[i][u], v)) u = up[i][u];
}
return up[0][u];
}
ll dist(int u, int v){
int ances = lca(u, v);
ll ans = 0;
for (int i = LG-1; i >= 0; i--){
if (!is_ancestor(up[i][u], ances)) {ans += (1 << i); u = up[i][u];}
if (!is_ancestor(up[i][v], ances)) {ans += (1 << i); v = up[i][v];}
}
return ans + (u != ances) + (v != ances);
}
ll f(int l, int r, int u){
// cout << l << ' ' << r << ' ' << u << ln;
int nxt;
ll ans = 0LL;
// go to subtree
for (auto v: adj[u]){
if (v == up[0][u]) continue;
nxt = answer(where[v], min(r, where[v] + sz[where[v]] - 1));
if (nxt) ans = max(ans, dist(u, nxt) + f(where[v], min(r, where[v] + sz[where[v]] - 1), nxt));
}
// go to top
nxt = answer(l, min(r, where[u]-1));
if (nxt) ans = max(ans, dist(u, nxt) + f(l, min(r, where[u]-1), nxt));
nxt = answer(max(l, where[u] + sz[where[u]]), r);
if (nxt) ans = max(ans, dist(u, nxt) + f(max(l, where[u] + sz[where[u]]), r, nxt));
return ans;
}
void solve(){
cin >> n;
for (int i = 1; i <= n; i++) cin >> p[i];
for (int i = 0; i < n-1; i++){
int u, v; cin >> u >> v;
adj[u].push_back(v);
adj[v].push_back(u);
}
root = -1;
for (int i = 1; i <= n; i++) if (p[i] == n) root = i;
dfs(root, root);
for (int i = 1; i < LG; i++){
for (int j = 1; j <= n; j++) up[i][j] = up[i-1][up[i-1][j]];
for (int j = 1; j + (1 << (i-1)) <= n; j++){
mx[i][j] = (p[mx[i-1][j]] > p[mx[i-1][j + (1 << (i-1))]])? mx[i-1][j]: mx[i-1][j + (1 << (i-1))];
}
}
cout << f(1, n, root) << ln;
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
// int TT; cin >> TT;
// while (TT--) {solve();}
solve();
}
