#include<bits/stdc++.h>
using namespace std;
#define S second
#define F first
#define ll long long
#define int long long
//#pragma GCC optimize("Ofast, unroll-loop")
//#pragma GCC target("avx,avx2")
#pragma GCC optimize("O3")
const int inf=0x3f3f3f3f;
const ll inff=0x3f3f3f3f3f3f3f3f;
const int X=1000000007;
int p[200005];
ll ans[200005];
vector<int> adj[200005];
ll dfs(int mx, int node, int pre, int l){
if(p[node]>mx) return 0;
ll ret=l+ans[node];
for(int i:adj[node]) if(i!=pre) ret=max(ret,dfs(mx,i,node,l+1));
return ret;
}
signed main(){
ios::sync_with_stdio(0), cin.tie(0);
int n; cin >> n;
for(int i=1 ; i<=n ; i++) cin >> p[i];
for(int i=1 ; i<n ; i++){
int a, b; cin >> a >> b;
adj[a].push_back(b);
adj[b].push_back(a);
}
vector<int> v;
for(int i=1 ; i<=n ; i++) v.push_back(i);
sort(v.begin(),v.end(),[&](int a, int b){
return p[a]<p[b];
});
for(int i:v){
ans[i]=dfs(p[i],i,0,0);
//cout << i << ' ' << ans[i] << '\n';
}
cout << *max_element(ans+1,ans+n+1) << '\n';
return 0;
}
void test(){
string ss; cin >> ss;
int n=ss.size();
ss='.'+ss;
while(1){
int t; cin >> t;
string s=ss;
s[t]='R';
while(t>=1&&t<=n){
for(int i=1 ; i<=n ; i++){
if(i==t) cout << '(';
cout << s[i];
if(i==t) cout << ')';
}
cout << '\n';
if(s[t]=='R') s[t]='B', t++;
else s[t]='R', t--;
}
}
}
