#include <iostream>
#include <iomanip>
#include <vector>
using namespace std;
int n, i, h[200010], u, v, p[200010], depth[200010];
vector<int> nb[200010];
long long dp[200010];
namespace euler
{
int t, sparseMin[19][400010], firstPoz[200010];
void appendNode(int node)
{
sparseMin[0][++t] = depth[node];
}
void appendNodeFirst(int node)
{
appendNode(node);
firstPoz[node] = t;
}
void computeSparse()
{
for (int i = 1; (1 << i) <= t; i++) {
for (int j = 1; j + (1 << i) - 1 <= t; j++) {
sparseMin[i][j] = min(sparseMin[i-1][j], sparseMin[i-1][j+(1<<(i-1))]);
}
}
}
int querySparseMin(int l, int r)
{
int len = 31 - __builtin_clz(r-l+1);
return min(sparseMin[len][l], sparseMin[len][r-(1<<len)+1]);
}
int getNodeDist(int a, int b)
{
int minDepth = querySparseMin(min(firstPoz[a], firstPoz[b]), max(firstPoz[a], firstPoz[b]));
return depth[a] + depth[b] - 2*minDepth;
}
}
namespace dsu
{
int nrdsu, dsu[200010], maxi[200010];
void init()
{
nrdsu = n;
for (int i = 1; i <= n; i++) {
dsu[i] = -1;
maxi[i] = i;
}
}
int getRoot(int node)
{
if (dsu[node] < 0) return node;
return dsu[node] = getRoot(dsu[node]);
}
bool dsuMerge(int a, int b)
{
a = getRoot(a);
b = getRoot(b);
if (a == b) return false;
if (dsu[a] > dsu[b]) swap(a, b);
dsu[a] += dsu[b];
dsu[b] = a;
maxi[a] = max(maxi[a], maxi[b]);
maxi[b] = 0;
nrdsu--;
return true;
}
}
void dfs1(int node)
{
euler::appendNodeFirst(node);
for (auto x : nb[node]) {
if (!p[x]) {
p[x] = node;
depth[x] = depth[node] + 1;
dfs1(x);
euler::appendNode(node);
}
}
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cin >> n;
for (i = 1; i <= n; i++) {
cin >> h[i];
}
for (i = 1; i < n; i++) {
cin >> u >> v;
u = h[u];
v = h[v];
nb[u].push_back(v);
nb[v].push_back(u);
}
p[1] = 1;
depth[1] = 1;
dfs1(1);
euler::computeSparse();
dsu::init();
dp[1] = 0;
for (int i = 2; i <= n; i++) {
for (auto x : nb[i]) {
if (x <= i) {
int bigboy = dsu::maxi[dsu::getRoot(x)];
dp[i] = max(dp[i], euler::getNodeDist(i, bigboy) + dp[bigboy]);
dsu::dsuMerge(i, x);
}
}
}
cout << dp[n];
return 0;
}
