#include<bits/stdc++.h>
using namespace std;
#define fast ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define in insert
#define all(x) x.begin(),x.end()
#define pb push_back
#define eb emplace_back
#define ff first
#define ss second
#define int long long
typedef long long ll;
typedef vector<int> vi;
typedef set<int> si;
typedef multiset<int> msi;
typedef pair<int, int> pii;
typedef vector<pii> vpii;
typedef pair<int, int> P;
template<typename T, typename U>
ostream & operator << (ostream &out, const pair<T, U> &c) {
out << c.first << ' ' << c.second;
return out;
}
template<typename T>
ostream & operator << (ostream &out, vector<T> &v) {
const int sz = v.size();
for (int i = 0; i < sz; i++) {
if (i) out << ' ';
out << v[i];
}
return out;
}
template<typename T>
istream & operator >> (istream &in, vector<T> &v) {
for (T &x : v) in >> x;
return in;
}
template<typename T, typename U>
istream & operator >> (istream &in, pair<T, U> &c) {
in >> c.first;
in >> c.second;
return in;
}
template<typename T>
void mxx(T &a, T b){if(b > a) a = b;}
template<typename T>
void mnn(T &a, T b){if(b < a) a = b;}
const int mxn = 2e5 + 10, inf = 1e18 + 10;
int p[mxn], vis[mxn];
vector<int> g[mxn];
pair<int, int> mx;
void dfs(int to, int fr, int dp = 1) {
if(p[mx.ff] < p[to]) mx = {to, dp};
for(int x : g[to]) {
if(vis[x] || x == fr) continue;
dfs(x, to, dp + 1);
}
}
int solve(int n) {
vis[n] = 1;
int ret = 0;
for(int x : g[n]) {
if(vis[x]) continue;
mx = {0, 0};
dfs(x, n);
mxx(ret, mx.ss + solve(mx.ff));
}
return ret;
}
void go() {
int n, root = 0;
cin >> n;
for(int i = 1; i <= n; i++) {
cin >> p[i];
if(p[i] == n) root = i;
}
for(int i = 1; i < n; i++) {
int x, y;
cin >> x >> y;
g[x].pb(y);
g[y].pb(x);
}
cout << solve(root) << '\n';
}
signed main() {
fast;
int t = 1;
// cin >> t;
while(t--) {
go();
}
return 0;
}
