#include<bits/stdc++.h>
#pragma GCC optimize("O3")
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
#pragma GCC target("avx2")
#define all(v) v.begin(),v.end()
using namespace std;
using ll = long long;
using P = pair<ll, ll>;
using PP = pair<ll, P>;
const ll n_ =2e5+100, inf = (ll)2e9 * (ll)1e9 + 7, mod = 998244353;
ll n, m, tc = 1, a, b, c, d, sum, x, y, z, base, ans, k;
ll gcd(ll x,ll y){
if(!y)return x;
return gcd(y,x%y);
}
vector<ll>v[n_];
ll arr[n_],parent[n_][21],dep[n_],par[n_],dp[n_];
ll find(ll x){
if(par[x]<0)return x;
return par[x]=find(par[x]);
}
void merge(ll x,ll y){
x=find(x),y=find(y);
if(x==y)return;
par[x]=y;
}
void dfs(int x, int par) {
dep[x] = dep[par] + 1;
for (int nxt : v[x]) {
if (nxt == par)continue;
parent[nxt][0] = x;
dfs(nxt, x);
}
}
int lca(int x, int y) {
if (dep[x] > dep[y])swap(x, y);//항상 y의 depth가 더 깊게 만들어주자!
for (int i = 20; i >= 0; i--)
if (dep[y] - dep[x] >= (1 << i))
y = parent[y][i];
if (x == y)return x;
for (int i = 20; i >= 0; i--) {
if (parent[x][i] != parent[y][i]) {
x = parent[x][i];
y = parent[y][i];
}
}
return parent[x][0];
}
ll dist(ll x,ll y){
ll z=lca(x,y);
return dep[x]-dep[z]+dep[y]-dep[z];
}
void solve(){
cin>>n;
vector<P>A;
for(int i=1;i<=n;i++)cin>>arr[i],A.push_back({arr[i],i});
sort(all(A));
for(int i=1;i<n;i++){
cin>>a>>b;
v[a].push_back(b);
v[b].push_back(a);
}
dfs(1,0);
for (int i = 1; i < 21; i++)
for (int j = 1; j <= n; j++)
parent[j][i] = parent[parent[j][i - 1]][i - 1];
memset(par,-1,sizeof(par));
for(auto [a,b]:A){
ll ret=0;
for(auto nxt:v[b]){
if(arr[nxt]>a)continue;
x=find(nxt);
ret=max(ret,dp[x]+dist(x,b));
merge(x,b);
}
dp[b]=ret;
//cout<<b<<' '<<dp[b]<<endl;
}
cout<<dp[A.back().second]<<endl;
}
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0), cout.tie(0);
//cin >> tc;
while (tc--)solve();
}
