#include<bits/stdc++.h>
#define int ll
#define ll long long
#define fr(i,j,k) for(register int i=j;i<=k;++i)
#define rf(i,j,k) for(register int i=j;i>=k;--i)
#define foredge(i,j) for(register int i=head[j];i;i=e[i].nxt)
#define pb push_back
#define Times printf("Time:%.3lf\n",clock()/CLOCKS_PER_SEC)
#define pii pair<int,int>
#define mk make_pair
using namespace std;
inline int read(){
	int x=0;
	bool f=0;
	char c=getchar();
	while(!isdigit(c)) f|=(c=='-'),c=getchar();
	while(isdigit(c)) x=(x<<3)+(x<<1)+(c^48),c=getchar();
	return f?-x:x;
}
inline void write(int x){
    if(x<0){putchar('-');x=-x;}
    if(x>9)write(x/10);
    putchar(x%10+'0');
}
inline void writeln(int x){write(x); puts("");}
inline void writepl(int x){write(x); putchar(' ');}
mt19937 rnd(chrono::steady_clock::now().time_since_epoch().count());
inline int randfind(int l,int r){return rnd()%(r-l+1)+l;}
//inline void init(){
//	int t=read();
//	while(t--) work();
//}
const int Maxn=2e5+10,inf=1e18,N=1e6;
struct line{int k,b;}ln[Maxn];
struct node{int id,ls,rs,tag;};
inline int getval(int id,int x){return ln[id].k*x+ln[id].b;}
inline bool chk(int id1,int id2,int x){return getval(id1,x)<getval(id2,x);}
int vis[Maxn];
namespace Tree{
	node e[Maxn*60];
	inline void change(int x,int k){
		if(!x) return;
		ln[x].b+=k;e[x].tag+=k;
	}
	inline void pushdown(int x){
		if(!e[x].tag) return;
		change(e[x].ls,e[x].tag);change(e[x].rs,e[x].tag);
		e[x].tag=0;
	}
	int nod;
	inline int update(int x,int l,int r,int id){
		if(!x) x=++nod;
		pushdown(x);
		if(!e[x].id){e[x].id=id;return x;}
		int mid;mid=(l+r)>>1;
		if(chk(id,e[x].id,mid)) swap(id,e[x].id);
		if(l==r) return x;
		if(chk(id,e[x].id,l)) e[x].ls=update(e[x].ls,l,mid,id);
		if(chk(id,e[x].id,r)) e[x].rs=update(e[x].rs,mid+1,r,id);
		return x;
	}
	inline int query(int k,int l,int r,int x){
		if(!x) return inf;
		pushdown(x);
		int ans=getval(e[x].id,k);
		if(l==r) return ans;
		int mid;mid=(l+r)>>1;
		if(k<=mid) ans=min(ans,query(k,l,mid,e[x].ls));
		else ans=min(ans,query(k,mid+1,r,e[x].rs));
		return ans;
	}
}
vector<int> vc[Maxn];
int rt[Maxn];
int idx,dfn[Maxn],siz[Maxn],son[Maxn];
inline void dfs(int x){
	dfn[x]=inf;
	if(vc[x].empty()) dfn[x]=++idx,siz[x]=1;
	for(auto y:vc[x]){
		dfs(y);
		siz[x]+=siz[y];dfn[x]=min(dfn[x],dfn[y]);
		if(siz[son[x]]<siz[y] || !son[x]) son[x]=y;
	}
}
int Ans[Maxn];
int c[Maxn];
inline void dp(int x){
	if(!son[x]){
		ln[dfn[x]]=(line){c[x],0};
		rt[x]=Tree::update(rt[x],1,N,dfn[x]);
		return;
	}
	int s=0;
	for(auto y:vc[x]){
		dp(y);
		Ans[y]=Tree::query(c[x],1,N,rt[y]);
		s+=Ans[y];
	}
	// cout<<"*"<<x<<' '<<s<<' '<<Ans[son[x]]<<endl;
	for(auto y:vc[x]) Tree::change(rt[y],s-Ans[y]);
	// Tree::change(rt[son[x]],s-Ans[son[x]]);
	rt[x]=rt[son[x]];
	for(auto y:vc[x]){
		if(y==son[x]) continue;
		fr(j,dfn[y],dfn[y]+siz[y]-1) rt[x]=Tree::update(rt[x],1,N,j);
	}
}
int n;
inline void init(){
	n=read();
	fr(i,2,n) vc[read()].pb(i);
	fr(i,1,n) c[i]=read();
}
inline void work(){
	dfs(1);dp(1);
	// cout<<siz[1]<<endl;
	writeln(Tree::query(c[1],1,N,rt[1]));
}
signed main(){
	// freopen("input.in","r",stdin);
	// freopen("output.out","w",stdout);
	init();work();
    // printf("\nTIME:%.3lf",(double)clock()/CLOCKS_PER_SEC);
	return 0;
}