#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const ll N = 2010,INF = 1e18;
template<typename T>void tomin(T& x,T y){x = min(x,y);}
template<typename T>void tomax(T& x,T y){x = max(x,y);}
//
int n,a[N],tag[N]; ll sz[N];
vector<int> e[N];

vector<int> sub[N];
ll dp[N][N];

void dfs1(int u){
    sz[u] = a[u]; 
    for(auto v : e[u])dfs1(v),sz[u] += sz[v];
}
void dfs2(int u){
    for(auto v : e[u])dfs2(v);

    if(tag[u]){
        dp[u][0] = dp[u][u] = 0;
        sub[u].push_back(u);
        return;
    }
    dp[u][0] = 0;
    for(auto v : e[u]){
        ll w = dp[v][0] + 1ll*a[u]*sz[v];
        for(auto x : sub[v]){
            dp[u][x] = dp[u][0] + dp[v][x];
            tomin(w,dp[v][x] + 1ll*a[u]*a[x]);
        }
        dp[u][0] += w;
        for(auto x : sub[u])dp[u][x] += w;
        for(auto x : sub[v])sub[u].push_back(x);
    }
}

int main(){
    ios::sync_with_stdio(false); cin.tie(0);
    cin>>n;
    for(int i=2,p;i<=n;i++){
        cin>>p;
        e[p].push_back(i);
    }
    for(int i=1;i<=n;i++)cin>>a[i];
    if(n==1){ cout<<"0\n"; return 0; }
    for(int i=2;i<=n;i++)tag[i] = (e[i].size() == 0);
    dfs1(1);

    for(int i=1;i<=n;i++)for(int j=0;j<=n;j++)dp[i][j] = INF;
    dfs2(1);

    cout<<dp[1][0]<<endl;

    return 0;
}