#include <stdio.h>
#include <algorithm>
#include <cstring>
#include <iostream>
using namespace std;

const int NR = 1e6 + 10;

int n;
int ans = 0;
int a[NR];
int lch[NR], rch[NR];

int check(int p, int q) {
    if (p == -1 && q == -1)
        return 0;

    if (p == -1 || q == -1 || a[p] != a[q])
        return -1;

    int r = check(rch[p], lch[q]), s = check(lch[p], rch[q]);

    if (r == -1 || s == -1)
        return -1;

    return r + s + 2;
}

int calc(int now) {
    if (now == -1)
        return 0;

    return max(check(lch[now], rch[now]) + 1, max(calc(lch[now]), calc(rch[now])));
}

int main() {
    ios::sync_with_stdio(0);

    cin >> n;

    for (int i = 1; i <= n; i++)
        cin >> a[i];

    for (int i = 1; i <= n; i++)
        cin >> lch[i] >> rch[i];

    cout << calc(1) << '\n';

    return 0;
}