#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define F first
#define S second
#define pb push_back
#define pii pair<int, int>
const int N = 2e5 + 5;
int n;
int p[N];
vector<int> g[N];
int mx[N], lab[N];
int h[N];
int up[N][18];
ll f[N];
void dfs(int u, int p) {
for (int v : g[u]) {
if (v == p) continue;
h[v] = h[u] + 1;
up[v][0] = u;
for (int i = 1; i < 18; i++) {
up[v][i] = up[up[v][i - 1]][i - 1];
}
dfs(v, u);
}
}
int lca(int u, int v) {
if (h[v] != h[u]) {
if (h[u] < h[v]) swap(u, v);
int k = h[u] - h[v];
for (int i = 0; (1 << i) <= k; i++) {
if (k >> i & 1) {
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];
}
int find(int u) {
return lab[u] < 0 ? u : lab[u] = find(lab[u]);
}
void join(int u, int v) {
if ((u = find(u)) == (v = find(v))) return;
if (lab[u] > lab[v]) swap(u, v);
lab[u] += lab[v];
mx[u] = max(mx[u], mx[v]);
lab[v] = u;
}
int dist(int u, int v) {
return h[u] + h[v] - 2 * h[lca(u, v)];
}
signed main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
cin >> n;
for (int i = 1; i <= n; i++) {
cin >> p[i];
mx[i] = i; lab[i] = -1;
}
for (int i = 1; i < n; i++) {
int u, v;
cin >> u >> v;
u = p[u];
v = p[v];
g[u].pb(v);
g[v].pb(u);
}
dfs(1, 0);
for (int i = 1; i <= n; i++) {
for (int j : g[i]) {
int v = mx[find(j)];
if (v < i) {
join(i, v);
f[i] = max(f[i], f[v] + dist(i, v));
}
}
}
cout << f[n];
}
