#include <bits/stdc++.h>
#define ll long long
#define pb push_back
#define eb emplace_back
#define pu push
#define ins insert
#define fi first
#define se second
#define all(a) a.begin(),a.end()
#define bruh ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define fu(x,a,b) for (auto x=a;x<=b;x++)
#define fd(x,a,b) for (auto x=a;x>=b;x--)
#define int ll
using namespace std;
//mt19937 mt(chrono::steady_clock::now().time_since_epoch().count());
/*
Competitive Programming notes that I need to study & fix my dumbass self:
1. Coding:
- Always be sure to check the memory of arrays (maybe use vectors), for loops
- Always try to maximize the memory if possible, even if you are going for subtasks
- Do not exploit #define int long long, it will kill you
2. Stress:
- Always try generating big testcases and try if they run
3. Time management:
- Don't overcommit or undercommit, always spend a certain amount of time to think a problem, don't just look at it and say I'm fucked
- Do not spend too much time coding brute-force solutions, they should be easily-codable solutions that don't take up too much time
Time management schedule:
Offline / LAH days (4 problems - 3h):
15' thinking of solution / idea
1. no idea: skip
2. yes idea: continue thinking for <= 15'
+ implementing: <= 20'
+ brute-force: <= 5'
+ test generator: <= 5'
I hate offline because I am dumb
*/
typedef pair<int, int> ii;
const int N = 2e5+5;
const int M = 20;
const int B = 750;
const int mod = 1e9+7;
const int inf = 1e18;
using cd = complex<double>;
const long double PI = acos(-1);
int power(int a,int b) {ll x = 1;if (a >= mod) a%=mod; while (b) {if (b & 1) x = x*a % mod;a = a*a % mod;b>>=1;}return x;}
int n;
int a[N], h[N];
vector<int> adj[N];
int up[N][M];
int dp[N];
void dfs(int u, int p)
{
up[u][0] = p;
for (int i = 1; i < M; i++) up[u][i] = up[up[u][i-1]][i-1];
for (auto v : adj[u])
{
if (v == p) continue;
h[v] = h[u] + 1;
dfs(v, u);
}
}
int lca(int u, int v)
{
if (h[u] < h[v]) swap(u,v);
int diff = h[u] - h[v];
for (int i = 0; i < M; i++) if (diff>>i & 1) u = up[u][i];
if (u == v) return u;
for (int i = M-1; i >= 0; i--) if (up[u][i] != up[v][i]) u = up[u][i], v = up[v][i];;
return up[u][0];
}
int dist(int u, int v)
{
return h[u] + h[v] - 2 * h[lca(u,v)];
}
int par[N], sz[N];
int find(int u)
{
if (u == par[u]) return u;
return par[u] = find(par[u]);
}
void merge(int u, int v)
{
u = find(u), v = find(v);
if (u == v) return;
if (a[u] < a[v]) swap(u,v);
par[v] = u;
sz[u] += sz[v];
}
bool cmp(int i, int j)
{
return a[i] < a[j];
}
void solve()
{
cin>>n;
int root = 0;
for (int i = 1; i <= n; i++)
{
cin>>a[i];
if (a[i] == n) root = i;
}
for (int i = 1; i < n; i++)
{
int u,v; cin>>u>>v;
adj[u].pb(v); adj[v].pb(u);
}
dfs(1, 0);
vector<int> id;
for (int i = 1; i <= n; i++)
{
id.pb(i);
par[i] = i; sz[i] = 1;
}
sort(all(id), cmp);
for (int i = 0; i < n; i++)
{
int u = id[i];
for (auto v : adj[u])
{
if (a[v] > a[u]) continue;
v = find(v);
dp[u] = max(dp[u], dp[v] + dist(u, v));
merge(u, v);
}
}
cout<<dp[root];
}
/*
Go through the mistakes you usually make and revise your code, for god's sake...
*/
signed main()
{
bruh
//freopen("input.inp","r",stdin);
//freopen("output.inp","w",stdout);
int t = 1;
// cin>>t;
while (t--)
{
solve();
cout<<"\n";
}
}
