#include <iostream>
#include<algorithm>
#include<vector>
using namespace std;

typedef long long ll;

ll nu[200001];

vector<int>nx[200001];

int dfs(int be, int ne, int f)
{
	ll su = 0;
	for (auto i : nx[ne])
	{
		if (i != be)
		{
			su+=dfs(ne, i,f+1);
		}
	}
	nu[ne] = su - f - nu[ne];
	return su + 1;
}

int main()
{
	int n;
	cin >> n;
	for (int i = 1; i <= n; i++)
	{
		cin >> nu[i];
	}
	for (int i = 2; i <= n; i++)
	{
		int be;
		cin >> be;
		nx[be].push_back(i);
	}
	dfs(0,1,0);
	sort(nu + 1, nu + 1 + n,greater<>());
	ll an = 0;
	for (int i = 1; i <= n; i+=2)
	{
		an += nu[i];
	}
	cout << an << endl;
	return 0;
}