#include <bits/stdc++.h>
using namespace std;
vector <vector<int> > connections, up, child;
vector <int> p, parent, depth;
int N, LOG;
void dfs(int a, int pa) {
for (int b : connections[a]) {
if(b == pa) continue;
depth[b] = depth[a] + 1;
up[b][0] = a;
for (int i(1); i < LOG; i++)
up[b][i] = up[ up[b][i - 1] ][i - 1];
dfs(b, a);
}
}
int lca(int a, int b) {
if (depth[a] < depth[b])
swap(a, b);
int k = depth[a] - depth[b];
for (int i(LOG); i >= 0; i--) {
if (k & (1 << i))
a = up[a][i];
}
if (a == b)
return a;
for (int i(LOG); i >= 0; i--) {
if (up[a][i] != up[b][i]) {
a = up[a][i];
b = up[b][i];
}
}
return up[a][0];
}
int Find(int x) {
if (x == parent[x]) return x;
return Find(parent[x]);
}
void Merge(int a, int b) {
int pb = Find(b);
child[a].push_back(pb);
parent[pb] = a;
}
long long score(int x) {
long long ans(0);
for (int i : child[x]) {
int root = lca(x, i);
ans = max(ans, score(i) + (long long)(depth[x] + depth[i] - 2 * depth[root]));
}
return ans;
}
int main() {
cin >> N;
LOG = ceil(log2(N));
connections.resize(N); p.resize(N), parent.resize(N); depth.resize(N); up.resize(N, vector<int> (LOG + 1, N - 1)); child.resize(N);
for (int i(0); i < N; i++) {
cin >> p[i];
p[i]--;
parent[i] = i;
}
for (int i(0); i < N - 1; i++) {
int a, b; cin >> a >> b;
a--; b--;
connections[p[a]].push_back(p[b]);
connections[p[b]].push_back(p[a]);
}
depth[N - 1] = 0;
dfs(N - 1, -1);
for (int i(1); i < N; i++) {
for (int j : connections[i]) {
if (j < i) Merge(i, j);
}
}
cout << score(N - 1) << '\n';
return 0;
}
