#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const int N = 200009;
ll n, h[N], w[N], f[N], lft[N], rgt[N];
int main() {
ios_base::sync_with_stdio(0); cin.tie(0);
cin >> n;
for (int i = 1; i <= n; i++) {
cin >> h[i];
w[h[i]] = i;
}
for (int i = 1; i < n; i++) {
int u, v;
cin >> u >> v;
}
vector < int > v;
for (int i = 1; i <= n; i++) {
while (!v.empty() && h[v.back()] <= h[i]) v.pop_back();
if (v.empty()) lft[i] = 0; else lft[i] = v.back();
v.push_back(i);
}
v.clear();
for (int i = n; i >= 1; i--) {
while (!v.empty() && h[v.back()] <= h[i]) v.pop_back();
if (v.empty()) rgt[i] = n + 1; else rgt[i] = v.back();
v.push_back(i);
}
for (int x = 1; x <= n; x++) {
f[lft[w[x]]] = max(f[lft[w[x]]], f[w[x]] + abs(lft[w[x]] - w[x]));
f[rgt[w[x]]] = max(f[rgt[w[x]]], f[w[x]] + abs(rgt[w[x]] - w[x]));
}
cout << *max_element(f + 1, f + n + 1);
}
