#include<bits/stdc++.h>
using namespace std;
const int N=1e5+10,M=1e7+10,W=1e6;
vector<int>to[N];
int fa[N],v[N],tt,n;
long long ans=0;
int rt[N],ls[M],rs[M];
struct Line
{
	long long k,b;
	long long at(int x){return k*x+b;}
};
struct node
{
	long long tg;Line val;
}tr[M];
void TG(int p,int v){if(p)tr[p].tg+=v,tr[p].val.b+=v;}
void PD(int p){if(tr[p].tg)TG(ls[p],tr[p].tg),TG(rs[p],tr[p].tg),tr[p].tg=0;}
void mdf(int&p,int l,int r,Line x)
{
	if(!p){tr[p=++tt]={0,x};return;}
	auto&Z=tr[p].val;
	if(l==r){if(Z.at(l)>x.at(l))tr[p].val=x;return;}
	int mid=l+r>>1;PD(p);
	if(Z.at(mid)>x.at(mid))swap(Z,x);
	if(Z.at(l)>x.at(l))mdf(ls[p],l,mid,x);
	if(Z.at(r)>x.at(r))mdf(rs[p],mid+1,r,x);
}
long long qry(int p,int l,int r,int x)
{
	if(!p)return 1e18;
	if(l==r)return tr[p].val.at(x);
	int mid=l+r>>1;PD(p);
	if(x<=mid)return min(tr[p].val.at(x),qry(ls[p],l,mid,x));
	return min(tr[p].val.at(x),qry(rs[p],mid+1,r,x));
}
int merge(int x,int y,int l,int r)
{
	if(!x||!y)return x|y;
	mdf(x,l,r,tr[y].val);
	if(l==r)return x;
	int mid=l+r>>1;PD(x),PD(y);
	ls[x]=merge(ls[x],ls[y],l,mid);
	rs[x]=merge(rs[x],rs[y],mid+1,r);
	return x;
}
void dfs(int u,int f)
{
	if(!to[u].size())return mdf(rt[u],1,W,{v[u],0});
	int w=0;
	for(int x:to[u])
	{
		dfs(x,u);
		if(!w)rt[u]=rt[x],w=1;
		else
		{
			long long v1=qry(rt[u],1,W,v[u]),v2=qry(rt[x],1,W,v[u]);
			TG(rt[u],v2),TG(rt[x],v1);rt[u]=merge(rt[u],rt[x],1,W);
		}
	}
}
int main()
{
	cin>>n;if(n==1)return puts("0"),0;
	for(int i=2;i<=n;++i)cin>>fa[i],to[fa[i]].push_back(i);
	for(int i=1;i<=n;++i)cin>>v[i];
	dfs(1,0);
	cout<<qry(rt[1],1,W,v[1])<<endl;
}