#include <bits/stdc++.h>
using namespace std;
#define int long long
#define ll long long
#define ld long double
#define all(v) v.begin(),v.end()
#define ar array
const int M = 1e6;
const int N = 26e4 + 20;
const int LOG = 31;
const int INF = 1e18;
const int MOD = 1e9 + 7;
const ld EPS = 1e-9;
inline void mm(int &x){x = (x % MOD + MOD) % MOD;}
inline void chmin(int &x, int y){x = min(x, y);}
inline void chmax(int &x, int y){x = max(x, y);}
#pragma GCC optimize("unroll-loops,O3")
int n;
int A[N];
vector<int> g[N];
int up[N][LOG];
int d[N];
void dfs(int x,int p){
up[x][0] = p;
for(int i = 1;i < LOG;i++)up[x][i] = up[up[x][i - 1]][i - 1];
for(auto u: g[x]){
if(u == p)continue;
d[u] = d[x] + 1;
dfs(u, x);
}
}
int lca(int a,int b){
if(d[a] < d[b])swap(a, b);
int k = d[a] - d[b];
for(int i = 0;i < LOG;i++){
if((1 << i) & k)a = up[a][i];
}
if(a == b)return a;
for(int i = LOG - 1;i >= 0;i--){
if(up[a][i] != up[b][i]){
a = up[a][i];
b = up[b][i];
}
}
return up[a][0];
}
int qry(int a,int b){
int l = lca(a, b);
return d[a] + d[b] - 2 * d[l];
}
int p[N];
int fnd(int x){
if(p[x] == x)return x;
return p[x] = fnd(p[x]);
}
void orz(){
cin>>n;
for(int i = 0;i < n;i++)cin>>A[i];
for(int i = 1;i < n;i++){
int a, b;
cin>>a>>b;
--a, --b;
g[a].push_back(b);
g[b].push_back(a);
}
dfs(0, 0);
iota(p, p + n, 0);
int ord[n];
iota(ord, ord + n, 0);
sort(ord, ord + n, [&](int a,int b)-> bool{
return A[a] < A[b];
});
int dp[n] = {0};
for(auto x: ord){
for(auto u: g[x]){
if(A[u] > A[x])continue;
u = fnd(u);
dp[x] = max(dp[x], dp[u] + qry(u, x));
p[u] = x;
}
}
cout<<dp[ord[n - 1]];
}
signed main(){ios_base::sync_with_stdio(false);cin.tie(0);
int t = 1;
//cin>>t;
while(t--)orz();
}
