#include <bits/stdc++.h>
using namespace std;
#define nl '\n'
struct DSU {
vector<int> e, mx; void init(int N, const vector<int>& A) { e = vector<int>(N, -1); mx = A; }
int get(int x) { return e[x] < 0 ? x : e[x] = get(e[x]); }
int getmx(int x) { return mx[get(x)]; }
bool unite(int x, int y) {
x = get(x), y = get(y);
if (x == y) return 0;
if (e[x] > e[y]) swap(x, y);
e[x] += e[y]; mx[x] = max(mx[x], mx[y]); e[y] = x; return 1;
}
};
using ll = long long;
const int LG = 20;
int main() {
cin.tie(0)->sync_with_stdio(0);
int N; cin >> N;
vector<int> A(N); for(auto& x : A) { cin >> x; --x; }
vector<int> P(N); for(int i = 0; i < N; i++) P[A[i]] = i;
vector<vector<int>> adj(N), ADJ(N);
for(int i = 0; i < N-1; i++) {
int u, v; cin >> u >> v; --u, --v;
if (A[u] < A[v]) swap(u, v);
adj[u].push_back(v);
adj[v].push_back(u);
ADJ[u].push_back(v);
}
vector<vector<int>> up(N, vector<int>(LG));
vector<int> dep(N);
function<void(int, int)> dfs = [&](int u, int p) {
up[u][0] = (p == -1 ? u : p);
dep[u] = (p == -1 ? 0 : dep[p] + 1);
for(int i = 1; i < LG; i++) up[u][i] = up[up[u][i-1]][i-1];
for(auto v : adj[u]) if (v != p) dfs(v, u);
};
auto jmp = [&](int u, int d) {
for(int i = 0; i < LG; i++) if ((d >> i) & 1) u = up[u][i];
return u;
};
auto lca = [&](int u, int v) {
if (dep[u] < dep[v]) swap(u, v);
u = jmp(u, dep[u] - dep[v]);
if (u == v) return u;
for(int i = LG - 1; i >= 0; i--) if (up[u][i] != up[v][i]) {
u = up[u][i], v = up[v][i];
}
return up[u][0];
};
auto dist = [&](int u, int v) {
return dep[u] + dep[v] - 2*dep[lca(u, v)];
};
vector<ll> dp(N);
dfs(0, -1);
DSU d; d.init(N, A);
for(int u = 0; u < N; u++) {
for(auto v : ADJ[P[u]]) {
int x = d.getmx(v);
// cout << u << " - " << P[u] << nl;
// cout << v << " <> " << x << nl;
dp[u] = max(dp[u], dp[x] + dist(P[u], P[x]));
}
for(auto v : ADJ[P[u]]) d.unite(P[u], v);
}
cout << dp[N - 1] << nl;
return 0;
}
/*
4
3 4 1 2
1 2
2 3
3 4
7
3 2 7 1 5 4 6
1 2
1 3
2 4
2 5
3 6
3 7
*/
