#include <bits/stdc++.h>
using namespace std;
#define nl '\n'
#define pb push_back
const int N = 2e5+3;
vector<int> g[N];
int w[N];
int p[N];
int d[N];
int rep[N];
int mx[N];
int dp[N];
int jmp[N][20];
int Find(int a) {
return (rep[a] == a)? a : rep[a] = Find(rep[a]);
}
void Union(int a, int b) {
a = Find(a), b = Find(b);
rep[b] = a;
}
void dfs(int v, int p) {
d[v] = d[p]+1;
jmp[v][0] = p;
for(int i=1; i<20; i++)
jmp[v][i] = jmp[jmp[v][i-1]][i-1];
for(auto u:g[v]) {
if(u == p) continue;
dfs(u, v);
}
}
int lca(int a, int b) {
if(d[a] < d[b]) swap(a, b);
for(int i=19; i>=0; i--) {
if(d[jmp[a][i]] >= d[b])
a = jmp[a][i];
}
for(int i=19; i>=0; i--) {
if(jmp[a][i] != jmp[b][i]) {
a = jmp[a][i];
b = jmp[b][i];
}
}
if(a == b) return a;
return jmp[a][0];
}
int dist(int a, int b) {
return d[a] + d[b] - 2*d[lca(a, b)];
}
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
int n;
cin >> n;
for(int i=1; i<=n; i++) {
cin >> w[i];
p[w[i]] = i;
rep[i] = i;
}
for(int i=1; i<n; i++) {
int a, b;
cin >> a >> b;
g[a].pb(b);
g[b].pb(a);
}
dfs(1, 0);
for(int i=1; i<=n; i++) {
int v = p[i];
for(auto u:g[v]) {
if(w[v] > w[u]) {
int a = Find(u);
dp[v] = max(dp[v], dp[a] + dist(v, a));
Union(v, a); // v > a
}
}
}
cout << dp[p[n]];
}
