#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define fi first
#define se second
#define pii pair<int,int>
#define pll pair<long long,long long>
#define pb push_back
#define debug(x) cerr<<#x<<"="<<x<<endl
#define pq priority_queue
#define inf 1ll<<60
#define rep(i,a,b) for (ll i=a;i<(b);i++)
#define MP make_pair
#define SZ(x) (int(x.size()))
#define mod 1000000007
#define ALL(x) x.begin(),x.end()
#define endl "\n"
void inc(ll &a,ll b) {a=(a+b)%mod;}
void dec(ll &a,ll b) {a=(a-b+mod)%mod;}
int prod(ll a,ll b) {return ll(a)*ll(b)%mod;}
int lowbit(ll x) {return x&(-x);}
ll p0w(ll base,ll p) {ll ret=1;while(p>0){if (p%2ll==1ll) ret=ret*base%mod;base=base*base%mod;p/=2ll;}return ret;}
const ll maxn=5555;
vector<ll>alist[maxn];
ll p[maxn],blocked[maxn];
ll dp[maxn];
ll dfs(ll u,ll fa){
blocked[u]=1;
ll tmp=0;
for(auto x:alist[u]){
if(x==fa)continue;
if(blocked[x])continue;
ll mx=x;
bool vis[maxn];
memset(vis,0,sizeof vis);
vis[x]=1;
ll dis[maxn];
memset(dis,0,sizeof dis);
dis[x]=1;
queue<ll>q;
q.push(x);
while(!q.empty()){
ll uu=q.front();
q.pop();
for(auto xx:alist[uu]){
if(blocked[xx])continue;
if(vis[xx])continue;
if(p[xx]>p[mx])mx=xx;
dis[xx]=dis[uu]+1;
vis[xx]=1;
q.push(xx);
}
}
//rep(i,1,10)cout<<dis[i]<<" ";
//cout<<endl;
//debug(mx);
tmp=max(tmp,dfs(mx,-1)+dis[mx]);
}
return dp[u]=tmp;
}
signed main(){
ios::sync_with_stdio(0);
cin.tie(0);
ll n;cin>>n;
rep(i,1,n+1)cin>>p[i];
rep(i,1,n){
ll a,b;cin>>a>>b;
alist[a].pb(b);
alist[b].pb(a);
}
ll st=0;
rep(i,1,n+1){
if(p[i]>p[st])st=i;
}
memset(dp,0,sizeof dp);
cout<<dfs(st,-1)<<endl;
return 0;
}
