#include <bits/stdc++.h>
using namespace std;
#define ff first
#define ss second
#define pb push_back
#define int long long
#define pint pair<int, int>
#define vint vector<int>
const int mod = 1e9 + 7;
const int mxn = 2e5 + 5;
const int say = INT_MAX / 2;
const int gex = INT_MIN / 2;
const long long oo = 1e18;
int p[mxn], pos[4 * mxn];
int n;
int build(int id, int L, int R) {
if(L == R) {
pos[id] = L;
return L;
}
int M = (L + R) / 2, x = 2 * id + 1, y = x + 1;
int aa = build(x, L, M);
int bb = build(y, M + 1, R);
if(p[aa] > p[bb]) {
pos[id] = aa;
return aa;
} else {
pos[id] = bb;
return bb;
}
}
int query(int id, int L, int R, int l, int r) {
if(L == l && r == R) {
return pos[id];
}
int M = (L + R) / 2, x = 2 * id + 1, y = x + 1;
if(r <= M) return query(x, L, M, l, r);
if(l > M) return query(y, M + 1, R, l, r);
int aa = query(x, L, M, l, M);
int bb = query(y, M + 1, R, M + 1, r);
if(p[aa] > p[bb]) return aa;
else return bb;
}
bool vis[mxn];
int dep[mxn];
void dfs(int l, int r, int par) {
// cout << "hi";
if(l > r || l < 0 || r > n) return;
if(l == r) {
dep[l] = dep[par] + 1;
return;
}
int id = query(0, 0, n - 1, l, r);
if(par == -1) dep[id] = 1;
else dep[id] = dep[par] + 1;
dfs(id + 1, r, id);
dfs(l, id - 1, id);
}
signed main(){
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
cin >> n;
// int p[n];
for(int i = 0; i < n; i++) cin >> p[i];
for(int i = 0; i < n - 1; i++) {
int x, y;
cin >> x >> y;
}
build(0, 0, n - 1);
dfs(0, n - 1, -1);
int ans = 0;
for(int i = 0; i < n; i++) {
ans = max(ans, dep[i]);
}
cout << ans << '\n';
// int q; cin >> q;
// while(q--) {
// int l, r; cin >> l >> r;
// cout << query(0, 0, n - 1, l , r) << '\n';
// }
return 0;
}
