#include <bits/stdc++.h>
#define ll long long
#define name "Cat Exercise"
#define fi(i, a, b) for(int i = a; i <= b; ++i)
#define fid(i, a, b) for(int i = a; i >= b; --i)
#define maxn (int) (2e5 + 7)
using namespace std;
int n;
int a[maxn], p[maxn], f[maxn];
int h[maxn], cha[maxn][18];
vector<int> edges[maxn];
struct DSU {
int lab[maxn];
DSU() { memset(lab, -1, sizeof lab); }
int get_rt(int u) { return lab[u] < 0 ? u : lab[u] = get_rt(lab[u]); }
void uni(int u, int v) {
int p = get_rt(u), q = get_rt(v); if(p == q) return;
lab[p] += lab[q], lab[q] = p;
}
} Dsu;
void dfs(int u, int par) {
for(int v : edges[u]) if(v != par) {
cha[v][0] = u, h[v] = h[u] + 1;
fi(i, 1, 17) cha[v][i] = cha[cha[v][i - 1]][i - 1];
dfs(v, u);
}
}
int lca(int u, int v) {
if(h[u] < h[v]) swap(u, v);
fid(i, 17, 0) if(h[u] - (1 << i) >= h[v]) u = cha[u][i];
fid(i, 17, 0) if(cha[u][i] != cha[v][i]) u = cha[u][i], v = cha[v][i];
return u == v ? u : cha[u][0];
}
int dist(int u, int v) {
return h[u] + h[v] - 2 * h[lca(u , v)];
}
void solve() {
cin >> n;
fi(i, 1, n) cin >> a[i], p[i] = i;
fi(i, 1, n - 1) {
int x, y; cin >> x >> y;
edges[x].push_back(y), edges[y].push_back(x);
}
dfs(1, 0);
sort(p + 1, p + 1 + n, [](int x, int y) { return a[x] < a[y]; });
fi(i, 1, n) {
int u = p[i];
for(int v : edges[u]) if(a[v] < a[u]) {
int p = Dsu.get_rt(v);
f[u] = max(f[u], f[p] + dist(u, p));
}
for(int v : edges[u]) if(a[v] < a[u]) Dsu.uni(u, v);
}
cout << f[p[n]];
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(0), cout.tie(0);
if(fopen(name".inp", "r")) {
freopen(name".inp", "r", stdin);
freopen(name".out", "w", stdout);
}
solve();
}
