#include<bits/stdc++.h>
#define For(i,a,b) for(int i=(a);i<=(b);++i)
#define Rep(i,a,b) for(int i=(a);i>=(b);--i)
#define int long long
using namespace std;
inline int read()
{
	char c=getchar();int x=0;bool f=0;
	for(;!isdigit(c);c=getchar())f^=!(c^45);
	for(;isdigit(c);c=getchar())x=(x<<1)+(x<<3)+(c^48);
	if(f)x=-x;return x;
}

#define fi first
#define se second
#define pb push_back
#define mkp make_pair
typedef pair<int,int>pii;
typedef vector<int>vi;

#define maxn 200005
#define inf 0x3f3f3f3f

int n,fa[maxn],c[maxn];
vi e[maxn];

int V=1e6;

#define N 20000007
int mn[maxn];
struct line{
	int k,b;
	int F(int x){return k*x+b;}
};
int add[N];
int rt[maxn],tot,val[N],ls[N],rs[N];
line t[N];

void pt(int p,int x){
	add[p]+=x;
	t[val[p]].b+=x;
}
void down(int p){
	if(add[p]){
		if(ls[p])pt(ls[p],add[p]);
		if(rs[p])pt(rs[p],add[p]);
		add[p]=0;
	}
}
void mdf(int&p,int l,int r,int x){
	if(!p){p=++tot;val[p]=x;return;}
	int mid=l+r>>1;
	if(t[x].F(mid)<t[val[p]].F(mid)) swap(x,val[p]);
	if(l==r)return;
	down(p);
	if(t[x].F(l)<t[val[p]].F(l))mdf(ls[p],l,mid,x);
	else if(t[x].F(r)<t[val[p]].F(r))mdf(rs[p],mid+1,r,x);
}
int merge(int u,int v,int l,int r){
	if(!u||!v)return u|v;
	if(l==r)return t[val[u]].F(l)<t[val[v]].F(l)?u:v;
	int mid=l+r>>1;
	down(u),down(v);
	ls[u]=merge(ls[u],ls[v],l,mid);
	rs[u]=merge(rs[u],rs[v],mid+1,r);
	mdf(u,l,r,val[v]);
	return u;
}
int ask(int p,int l,int r,int x){
	if(!p)return 1e18;
	if(l==r)return t[val[p]].F(x);
	int mid=l+r>>1,res=t[val[p]].F(x); down(p);
	if(x<=mid)res=min(res,ask(ls[p],l,mid,x));
	else res=min(res,ask(rs[p],mid+1,r,x));
	return res;
}

void solve(int u)
{
	if(!e[u].size()){
		t[u]=(line){c[u],0};
		mdf(rt[u],1,V,u);
	//	cout<<"qwq "<<ask(rt[u],1,V,1)<<'\n';
		return;
	}
	int sum=0;
	for(int v:e[u]){
		solve(v);
		mn[v]=ask(rt[v],1,V,c[u]);
	//	cout<<"mn: "<<v<<" "<<mn[v]<<endl;
		sum+=mn[v];
	}
	if(u!=1){
		for(int v:e[u]){
			pt(rt[v],sum-mn[v]);
			rt[u]=merge(rt[u],rt[v],1,V);
		}
	}else{
		cout<<sum<<"\n";
	} 
}

void work()
{
	n=read();
	For(i,2,n)fa[i]=read(),e[fa[i]].pb(i);
	For(i,1,n)c[i]=read();
	solve(1);
}

signed main()
{
	int T=1;
	while(T--)work();
	return 0;
}