#include <bits/stdc++.h>
struct DSU {
int n;
std::vector<int> p, mx;
DSU() = default;
DSU(int n) : n(n), p(n, 0) {
std::iota(p.begin(), p.end(), 0);
mx = p;
}
int get(int u) {
while (u != p[u]) u = p[u] = p[p[u]];
return u;
}
void unite(int u, int v) {
mx[get(u)] = std::max(mx[get(u)], mx[get(v)]);
p[get(v)] = get(u);
}
int max(int u) {
return mx[get(u)];
}
};
struct segtree {
int n;
std::vector<std::pair<int, int>> tr;
segtree() = default;
segtree(int n) : n(n), tr(2 * n, {1e9, 1e9}) {}
segtree(std::vector<std::pair<int, int>> a) {
n = a.size();
tr.resize(2 * n);
for (int i = 0; i < n; ++i) {
tr[i + n] = a[i];
}
for (int i = n - 1; i; --i) {
tr[i] = std::min(tr[i << 1], tr[i << 1 | 1]);
}
}
std::pair<int, int> get(int l, int r) {
std::pair<int, int> res = {1e9, 1e9};
for (l += n, r += n; l <= r; l >>= 1, r >>= 1) {
if (l & 1) res = std::min(res, tr[l++]);
if (~r & 1) res = std::min(res, tr[r--]);
}
return res;
}
};
int main() {
std::cin.tie(nullptr)->sync_with_stdio(false);
int n;
std::cin >> n;
std::vector<int> p(n);
for (auto& i : p) std::cin >> i, --i;
std::vector<std::vector<int>> g(n);
for (int i = 0; i < n - 1; ++i) {
int u, v;
std::cin >> u >> v;
--u, --v;
u = p[u];
v = p[v];
g[u].push_back(v);
g[v].push_back(u);
}
std::vector<int> depth(n), pos(n);
std::vector<std::pair<int, int>> ss;
auto dfs = [&](auto dfs, int u, int p) -> void {
ss.emplace_back(depth[u], u);
pos[u] = ss.size() - 1;
for (auto to : g[u]) {
if (to != p) {
depth[to] = depth[u] + 1;
dfs(dfs, to, u);
ss.emplace_back(depth[u], u);
}
}
};
dfs(dfs, 0, -1);
segtree tr(ss);
auto lca = [&](int u, int v) -> int {
u = pos[u];
v = pos[v];
if (u > v) std::swap(u, v);
return tr.get(u, v).second;
};
auto dist = [&](int u, int v) -> int {
return depth[u] + depth[v] - 2 * depth[lca(u, v)];
};
std::vector<long long> dp(n);
DSU dsu(n);
for (int i = 0; i < n; ++i) {
for (auto j : g[i]) {
if (j > i) continue;
dp[i] = std::max(dp[i], dp[dsu.max(j)] + dist(i, dsu.max(j)));
dsu.unite(i, j);
}
}
std::cout << dp[n - 1];
}
