#include <bits/stdc++.h>
using namespace std;
#define int long long
#define INF 1000000000000000000
#define MOD 998244353
vector<int> adj[200000];
int p[200000][18], depth[200000], dp[200000], pa[200000];
int root(int x) {
if(pa[x] == x) return x;
else return pa[x] = root(pa[x]);
}
void merge(int x, int y) {
x = root(x); y = root(y);
if(x == y) return;
if(x > y) swap(x, y);
pa[x] = y;
}
void dfs(int x, int par, int d) {
depth[x] = d;
p[x][0] = par;
for(int i = 1; i < 18; i++) {
if(p[x][i-1] == -1) break;
p[x][i] = p[p[x][i-1]][i-1];
}
for(int i : adj[x]) if(i != par) dfs(i, x, d+1);
}
int lca(int x, int y) {
if(depth[x] < depth[y]) swap(x, y);
int h = depth[x]-depth[y];
for(int i = 0; i < 18; i++) {
if(h&(1<<i)) x = p[x][i];
}
if(x == y) return x;
for(int i = 17; i >= 0; i--) {
if(p[x][i] != p[y][i]) {
x = p[x][i]; y = p[y][i];
}
}
return p[x][0];
}
int dist(int x, int y) {
return depth[x]+depth[y]-2*depth[lca(x, y)];
}
int32_t main() {
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
int n, x, y;
cin >> n;
int p[n];
for(int i = 0; i < n; i++) {
cin >> p[i];
p[i]--;
}
for(int i = 0; i < n-1; i++) {
cin >> x >> y;
x--; y--;
adj[p[x]].push_back(p[y]);
adj[p[y]].push_back(p[x]);
}
memset(p, -1, sizeof(p));
for(int i = 0; i < n; i++) pa[i] = i;
dfs(0, -1, 0);
for(int i = 0; i < n; i++) {
for(int j : adj[i]) if(j < i) {
int rt = root(j);
dp[i] = max(dp[i], dp[rt]+dist(rt, i));
merge(i, j);
}
}
cout << dp[n-1];
}
