#include <bits/stdc++.h>
using namespace std;
const int N = 200005, L = 17;
int n, p[N], po[N];
vector<int> adj[N];
int h[N], up[N][L + 1];
void DFS(int u, int pa) {
for (int v: adj[u]) {
if (v == pa) {
continue;
}
h[v] = h[u] + 1;
up[v][0] = u;
for (int k = 1; k <= L; k++) {
up[v][k] = up[up[v][k - 1]][k - 1];
}
DFS(v, u);
}
}
int LCA(int u, int v) {
if (h[u] < h[v]) swap(u, v);
int d = h[u] - h[v];
for (int k = 0; k <= L; k++) {
if ((d >> k) & 1) {
u = up[u][k];
}
}
if (u == v) {
return u;
}
for (int k = L; k >= 0; k--) {
if (up[u][k] ^ up[v][k]) {
u = up[u][k];
v = up[v][k];
}
}
return up[u][0];
}
int dist(int u, int v) {
return h[u] + h[v] - 2 * h[LCA(u, v)];
}
int root[N];
int find(int u) {
return u ^ root[u] ? root[u] = find(root[u]) : u;
}
long long dp[N];
void solve(void) {
cin >> n;
for (int i = 1; i <= n; i++) {
cin >> p[i];
po[p[i]] = i;
}
for (int i = 1, u, v; i < n; i++) {
cin >> u >> v;
adj[u].emplace_back(v);
adj[v].emplace_back(u);
}
h[1] = 0;
DFS(1, 1);
iota(root + 1, root + 1 + n, 1);
for (int num = 1; num <= n; num++) {
int u = po[num];
for (int v: adj[u]) {
if (p[v] < p[u]) {
int rv = find(v);
dp[u] = max(dp[u], dp[rv] + dist(u, rv));
root[rv] = u;
}
}
}
cout << dp[po[n]];
}
signed main(void) {
ios::sync_with_stdio(false); cin.tie(nullptr);
solve();
return 0;
}
