#include <bits/stdc++.h>
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define int long long
#define yes() cout << "YES\n"
#define no() cout << "NO\n"
using namespace std;
using ll = long long;
using ull = unsigned long long;
using ld = long double;
const int inf = 1e18;
const int mod = 1e9 + 7;
const int maxn = 1e7 + 5e6;
const int mod1 = 998244353;
const int mod2 = 1e18 + 1;
const int mod3 = 1e9 + 9;
const int mod4 = 333333333;
const int mod5 = 200000;
const int mod6 = 10007;
const int k = 300;
const int w = 1e5;
const ld EPS = 1e-8;
int LOG = 30;
vector<int> a;
vector<vector<int>> g;
vector<int> used;
vector<int> dp;
struct e {
int cost, v, dist;
};
e get(int v, int p, int d) {
e ans = {a[v], v, d};
for (int& u : g[v]) {
if (u != p && !used[u]) {
e tmp = get(u, v, d + 1);
if (tmp.cost > ans.cost) ans = tmp;
}
}
return ans;
}
void dfs(int v, int p) {
used[v] = 1;
for (int& u : g[v]) {
if (u != p && !used[u]) {
e res = get(u, v, 1);
int best = res.v;
dfs(best, best);
dp[v] = max(dp[v], dp[best] + res.dist);
}
}
}
void solve() {
int n;
cin >> n;
a.assign(n, 0);
g.assign(n, vector<int> ());
used.assign(n, 0);
dp.assign(n, 0);
for (int& i : a) cin >> i;
for (int i = 0; i < n - 1; i++) {
int u, v;
cin >> u >> v;
u--, v--;
g[u].push_back(v), g[v].push_back(u);
}
int idx = -1;
for (int i = 0; i < n; i++) if (a[i] == n) idx = i;
dfs(idx, idx);
cout << dp[idx] << "\n";
}
signed main() {
// cout.precision(16);
ios::sync_with_stdio(false);
cin.tie(nullptr);
int t = 1;
// cin >> t;
while (t--) {
solve();
}
}
