#include<cstdio>
#include<cstring>
#include<algorithm>
#include<vector>
#include<cassert>
#include<set>
#include<random>
#include<chrono>
#include<bitset>
#include<map>
#include<queue>
#include<cstdlib>
#include<cmath>
#include<iostream>
#include<string>
#define eb emplace_back

using namespace std;
const int maxn=2e5+10, maxm=11+10, inf=2e9+10, P=1e9+7;
const double eps=1e-10, pi=acos(-1.0);
typedef long long LL;
typedef unsigned long long ULL;
const LL INF=4e18;
typedef pair<LL, int> pli;
typedef pair<int, int> pii;
typedef pair<LL, LL> pll;
inline int read() {
	int x=0, f=1; char c=getchar();
	for(; c<'0'||c>'9'; c=getchar()) if(c=='-') f=0;
	for(; c>='0'&&c<='9'; c=getchar()) x=x*10+c-'0';
	return f?x:-x;
}
mt19937 rnd((unsigned)chrono::steady_clock::now().time_since_epoch().count());
inline int ksm(int x, int y) {
	int s=1;
	for(; y; y>>=1, x=1LL*x*x%P)
		if(y&1) s=1LL*s*x%P;
	return s;
}
inline int add(int x, int y) {x+=y; return x>=P?x-P:x;}
inline int del(int x, int y) {x-=y; return x<0?x+P:x;}
LL gcd(LL x, LL y) {return y?gcd(y, x%y):x;}

struct pj{
	int lc, rc, sz; LL ad;
	LL x, y;
} tr[maxn]; int cnt;

inline void update(int u) {
	tr[u].sz=tr[tr[u].lc].sz+tr[tr[u].rc].sz+1;
}
inline int cmp(int x, int y) { //key(x)>key(y)
	return rnd()%(tr[x].sz+tr[y].sz)<tr[x].sz;
}
inline int add_n(LL x, LL y) {
	int u=++cnt;
	tr[u].x=x; tr[u].y=y; tr[u].sz=1;
	return u;
}
inline void pushdown(int u) {
	if(tr[u].ad==0) return;
	if(tr[u].lc) tr[tr[u].lc].y+=tr[u].ad, tr[tr[u].lc].ad+=tr[u].ad;
	if(tr[u].rc) tr[tr[u].rc].y+=tr[u].ad, tr[tr[u].rc].ad+=tr[u].ad;
	tr[u].ad=0;
}
void splitrk(int u, int rk, int& x, int& y) {//x:<=rk  y:>rk
	if(u==0) {x=y=0; return;}
	pushdown(u);
	if(tr[tr[u].lc].sz+1<=rk) {
		x=u; splitrk(tr[u].rc, rk-(tr[tr[u].lc].sz+1), tr[x].rc, y);
		update(x);
	} else {
		y=u; splitrk(tr[u].lc, rk, x, tr[y].lc);
		update(y);
	}
}
void splitval(int u, LL val, int& x, int& y) {//x:<=val  y:>val
	if(u==0) {x=y=0; return;}
	pushdown(u);
	if(tr[u].x<=val) {
		x=u; splitval(tr[u].rc, val, tr[x].rc, y);
		update(x);
	} else {
		y=u; splitval(tr[u].lc, val, x, tr[y].lc);
		update(y);
	}
}
int merge(int x, int y) {
	if(x==0||y==0) return x^y;
	int u;
	pushdown(x); pushdown(y);
	if(cmp(x, y)) u=x, tr[u].rc=merge(tr[x].rc, y);
		else u=y, tr[u].lc=merge(x, tr[y].lc);
	update(u);
	return u;
}

struct tg{int y, nxt;} g[maxn];
int len, la[maxn];
inline void add_e(int x, int y) {g[++len].y=y; g[len].nxt=la[x]; la[x]=len;}

LL f[maxn], c[maxn];
int rt[maxn], sz[maxn], lst[maxn], tot;
void getlst(int x) {
//	assert(x>0);
	pushdown(x);
	if(tr[x].lc) getlst(tr[x].lc);
	lst[++tot]=x;
	if(tr[x].rc) getlst(tr[x].rc);
}
inline int cmpslope(LL x, LL y, LL z, LL w) {
	//x/y>=z/w
	assert(y>0&&w>0);
	return (__int128)x*w>=(__int128)y*z;
}
void print(int u) {
	pushdown(u);
	if(tr[u].lc) print(tr[u].lc);
	printf("(%lld, %lld) ", tr[u].x, tr[u].y);
	if(tr[u].rc) print(tr[u].rc);
}
inline void inspoint(int& nw, int oth) {
	//tot=0; 
	//getlst(nw);
	//printf("merge\n");
	//for(int i=1; i<=tot; ++i) printf("(%lld, %lld) ", tr[lst[i]].x, tr[lst[i]].y);
	//puts("");
	//puts("in");
	tot=0;
	getlst(oth);
	//for(int i=1; i<=tot; ++i) printf("(%lld, %lld) ", tr[lst[i]].x, tr[lst[i]].y);
	//puts("");
	for(int t=1; t<=tot; ++t) {
		LL x=tr[lst[t]].x, y=tr[lst[t]].y;
		tr[lst[t]].lc=tr[lst[t]].rc=0; tr[lst[t]].ad=0;
		tr[lst[t]].sz=1;
		int u, v, w, p;
		splitval(nw, x, w, v);
		splitval(w, x-1, u, p);
		if(p!=0&&y>=tr[p].y) {nw=merge(merge(u, p), v); continue;}
		int l=0, lp=0, rp=0, r=0;
	//	printf("u=%d v=%d\n", u, v);
		if(u) splitrk(u, tr[u].sz-1, l, lp);
		if(v) splitrk(v, 1, rp, r);
		//printf("l=%d lp=%d rp=%d r=%d\n", l, lp, rp, r);
		if(lp>0&&rp>0) { 
			if(cmpslope(y-tr[lp].y, x-tr[lp].x, tr[rp].y-tr[lp].y, tr[rp].x-tr[lp].x)) {
				nw=merge(merge(l, lp), merge(rp, r));
				//printf("ins (%lld, %lld)\n", x, y);
				//print(nw);
				//puts("");
				continue;
			}
		}
	//	printf("l=%d lp=%d rp=%d r=%d\n", l, lp, rp, r);
		while(l) {
			int nl, np;
			splitrk(l, tr[l].sz-1, nl, np);
			if(cmpslope(tr[lp].y-tr[np].y, tr[lp].x-tr[np].x, y-tr[np].y, x-tr[np].x)) {
				l=nl; lp=np;
			//	printf("del\n");
			} else {l=merge(nl, np); break;}
		}
		while(r) {
			int nr, np;
			splitrk(r, 1, np, nr);
			if(cmpslope(tr[np].y-y, tr[np].x-x, tr[np].y-tr[rp].y, tr[np].x-tr[rp].x)) {
				r=nr; rp=np;
			} else {r=merge(np, nr); break;}
		}
		nw=merge(merge(merge(l, lp), lst[t]), merge(rp, r));
		//printf("ins (%lld, %lld)\n", x, y);
		//print(nw);
		//puts("");
	}
	//printf("result:");
	//tot=0;
	//getlst(nw);
	//for(int i=1; i<=tot; ++i) printf("(%lld, %lld) ", tr[lst[i]].x, tr[lst[i]].y);
	//puts("");
	//puts("out");
}

void dfs(int x, int F) {
	sz[x]=1;
	if(la[x]==0) {
		f[x]=c[F]*c[x];
		rt[x]=add_n(c[x], 0);
		return;
	}
	LL sum=0; int p=0;
	for(int i=la[x]; i; i=g[i].nxt) {
		int y=g[i].y;
		dfs(y, x);
		sum+=f[y]; sz[x]+=sz[y];
		if(sz[y]>sz[p]) p=y;
	}
	rt[x]=rt[p]; tr[rt[x]].ad+=sum-f[p]; tr[rt[x]].y+=sum-f[p];
	
	//if(x==2) {
	//	print(rt[x]);
	//}
	for(int i=la[x]; i; i=g[i].nxt) {
		int y=g[i].y;
		if(y!=p) tr[rt[y]].ad+=sum-f[y], tr[rt[y]].y+=sum-f[y], inspoint(rt[x], rt[y]);
	}
	//calc f
	//k=-c[F]
	int u=rt[x];
	pll rb=make_pair(-1, -1);
	f[x]=INF;
	while(1) {
		//getnxt
	//	if(x==2) printf(" u=%d\n", u);
		f[x]=min(f[x], tr[u].y+tr[u].x*c[F]);
		pushdown(u);
		pll nxt;
		if(tr[u].rc) {
			int t=tr[u].rc;
			while(tr[t].lc) pushdown(t), t=tr[t].lc;
			nxt=make_pair(tr[t].x, tr[t].y);
		} else nxt=rb;
		if(nxt.first==-1) {
			if(tr[u].lc==0) break;
			rb=make_pair(tr[u].x, tr[u].y);
			u=tr[u].lc; 
		} else {
			if(cmpslope(nxt.second-tr[u].y, nxt.first-tr[u].x, -c[F], 1)) {
				if(tr[u].lc==0) break;
				rb=make_pair(tr[u].x, tr[u].y);
				u=tr[u].lc;
			} else {
				if(tr[u].rc==0) break;
				u=tr[u].rc;
			}
		}
	}
}

void prtsbt(int x) {
//	printf("x=%d c=%lld\n", x, c[x]);
	for(int i=la[x]; i; i=g[i].nxt) {
		int y=g[i].y;
		printf("%d---%d\n", x, y);
		prtsbt(y);
	}
}
int main() {
	//freopen("3.in", "r", stdin);
	//freopen("3.out", "w", stdout);
	int n=read();
	for(int i=2, x; i<=n; ++i) {
		x=read(); add_e(x, i);
	}
	for(int i=1; i<=n; ++i) c[i]=read();

	LL prt=0;
	for(int i=la[1]; i; i=g[i].nxt) {
		int y=g[i].y;
		dfs(y, 1);
		prt+=f[y];
	}
	//printf("fat=%d c=%lld\n", fat, c[fat]);
//	for(int i=2; i<=n; ++i) printf("f[%d]=%lld\n", i, f[i]);
	printf("%lld", prt);
	return 0;
}