#include <bits/stdc++.h>
using namespace std;
// #define int long long
#define ll long long
#define ff first
#define ss second
#define pint pair < int , int >
#define fast ios_base::sync_with_stdio(NULL); cin.tie(NULL)
typedef vector < int > vint;
const int inf = 1e9 + 9;
const int mxn = 2e5 + 2;
const int mod = 1e9 + 7;
int a[mxn];
struct node {
int tl , tm , tr;
int id;
node *left , *right;
node (int l , int r) {
tl = l , tr = r , tm = (l + r) / 2;
if (tl == tr) {
id = tl;
return;
}
left = new node(tl , tm);
right = new node(tm+1 , tr);
id = (a[left->id] > a[right->id]) ? left->id : right->id;
}
int query(int l , int r) {
if (tl == l && tr == r) return id;
if (r <= tm) return left -> query(l , r);
else if (l > tm) return right -> query(l , r);
int idl = left -> query(l , tm);
int idr = right -> query(tm+1 , r);
return (a[idl] > a[idr]) ? idl : idr;
}
} *root;
int dfs(int l , int r) {
if (l == r) return 0;
int x = root -> query(l , r);
int t1 = -inf , t2 = -inf;
if (x != r) t1 = root -> query(x+1 , r) - x + dfs(x+1 , r);
if (x != l) t2 = x - root -> query(l , x-1) + dfs(l , x-1);
return max(t1 , t2);
}
int main() {
int n;
cin >> n;
for (int i = 1; i <= n; i++) {
cin >> a[i];
}
for (int i = 0; i < n-1; i++) {
int x , y;
cin >> x >> y;
}
root = new node(1 , n);
cout << dfs(1 , n) << '\n';
return 0;
}
