#include <bits/stdc++.h>
using namespace std;
const int maxn = 2e5 + 5;
int n, a[maxn], f[maxn];
vector<int> g[maxn];

void dfs(int u) {
	f[u] = g[u].size() ? 1e9 : a[u];
	for (auto v : g[u])
		dfs(v), f[u] = min(f[u], f[v]);
	if (u == 1)
		cout << a[u] + f[u] << endl;
	else if (f[u] > a[u])
		f[u] = (f[u] + a[u]) / 2;
}

int main() {
	cin >> n;
	for (int i = 1; i <= n; i++)
		cin >> a[i];
	for (int i = 2; i <= n; i++) {
		int p;
		cin >> p;
		g[p].push_back(i);
	}
	dfs(1);
	return 0;
}