#include <bits/stdc++.h>
    
using namespace std;
    
typedef long long ll;

const int  N = (int)2e5 + 12, MOD = 998244353;

const int B = 19;
int n, p[N],f[N], up[N][19], timer, tin[N], tout[N], dep[N];
ll dp[N];
vector<int> g[N], G[N];

int get(int v) {
    if(f[v] == v) return v;
    return f[v] = get(f[v]);
}
void dfs(int v, int pr = 1) {
    tin[v] = ++timer;
    up[v][0] = pr;
    for(int i = 1; i < B; i++) {
        up[v][i] = up[up[v][i - 1]][i - 1];
    }
    for(int to : G[v]) if(to != pr) {
        dep[to] = dep[v] + 1;
        dfs(to, v);
    }
    tout[v] = ++timer;
}
bool is(int v, int u) {
    return (tin[v] <= tin[u] && tout[v] >= tout[u]);
}
int lca(int v, int u) {
    if(is(v, u)) return v;
    if(is(u, v)) return u;
    for(int i = B - 1; i >= 0; i--) {
        if(!is(up[v][i], u)) {
            v = up[v][i];
        }
    }
    return up[v][0];
}
int dist(int x, int y) {
    return dep[x] + dep[y] - dep[lca(x, y)] * 2;
}
void test() { 
    cin >> n;
    for(int i = 1; i <= n; i++) {
        cin >> p[i];
        f[i] = i;
    }
    for(int i = 1; i <= n -1; i++) {
        int a, b;
        cin >> a >> b;a = p[a];b = p[b];

        g[b].push_back(a);
        
        G[a].push_back(b);
        G[b].push_back(a);
    }
    dfs(1);
    for(int i = 1; i <= n; i++) {
        for(int to : g[i]) {
            dp[i] = max(dp[i], dp[get(to)] + dist(get(to), to) + 1);
            f[get(to)] = i;
        }
    }
    cout << dp[n] << '\n';
}
int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(0);

    int t = 1;
    // cin >> t;

    while(t--) 
        test();
}