#include <iostream>
#include <vector>
#include <math.h>
using namespace std;
constexpr int N = 2e5 + 5;
constexpr int logN = static_cast<int>(log2(N));
int n;
int at[N];
vector<int> tree[N];
int timer;
int tin[N], tout[N];
int depth[N];
int up[N][logN + 1];
void dfs(int u, int p) {
up[u][0] = p;
for (int i = 0; i < logN; i++) {
up[u][i + 1] = up[up[u][i]][i];
}
tin[u] = ++timer;
for (int v : tree[u]) {
if (v == p) continue;
depth[v] = depth[u] + 1;
dfs(v, u);
}
tout[u] = timer;
}
inline bool is_ancestor(int a, int d) {
return tin[a] <= tin[d] && tin[d] <= tout[a];
}
int lca(int u, int v) {
if (is_ancestor(u, v)) return u;
if (is_ancestor(v, u)) return v;
for (int i = logN; i >= 0; i--) {
if (is_ancestor(up[u][i], v)) continue;
u = up[u][i];
}
return up[u][0];
}
inline int dist(int u, int v) {
return depth[u] + depth[v] - 2 * depth[lca(u, v)];
}
long long dp[N];
int headquarter[N];
int parent[N];
int renk[N];
inline bool is_set(int u) {
return parent[u] != 0;
}
inline void make_set(int u) {
parent[u] = u;
}
int find_set(int u) {
if (parent[u] == u) return u;
return parent[u] = find_set(parent[u]);
}
inline void union_sets(int u, int v) {
u = find_set(u);
v = find_set(v);
if (renk[u] >= renk[v]) {
if (renk[u] == renk[v]) renk[v]++;
parent[v] = u;
} else {
parent[u] = v;
}
}
signed main()
{
ios::sync_with_stdio(false);
cin.tie(NULL);
cout.tie(NULL);
// freopen("input.txt", "r", stdin);
cin >> n;
for (int u = 1; u <= n; u++) {
int h;
cin >> h;
at[h] = u;
}
for (int e = 1; e < n; e++) {
int u, v;
cin >> u >> v;
tree[u].push_back(v);
tree[v].push_back(u);
}
dfs(1, 1);
for (int h = 1; h <= n; h++) {
int u = at[h];
long long maxd = 0;
make_set(u);
for (int v : tree[u]) {
if (!is_set(v)) continue;
maxd = max(maxd, dp[find_set(v)] + dist(u, headquarter[find_set(v)]));
union_sets(u, v);
}
dp[find_set(u)] = maxd;
headquarter[find_set(u)] = u;
}
cout << dp[at[n]];
return 0;
}
