#include <bits/stdc++.h>
#define fi first
#define se second
#define rep(i,n) for(int i = 0; i < (n); ++i)
#define rrep(i,n) for(int i = 1; i <= (n); ++i)
#define drep(i,n) for(int i = (n)-1; i >= 0; --i)
#define srep(i,s,t) for (int i = s; i < t; ++i)
#define rng(a) a.begin(),a.end()
#define maxs(x,y) (x = max(x,y))
#define mins(x,y) (x = min(x,y))
#define limit(x,l,r) max(l,min(x,r))
#define lims(x,l,r) (x = max(l,min(x,r)))
#define isin(x,l,r) ((l) <= (x) && (x) < (r))
#define pb push_back
#define sz(x) (int)(x).size()
#define pcnt __builtin_popcountll
#define uni(x) x.erase(unique(rng(x)),x.end())
#define snuke srand((unsigned)clock()+(unsigned)time(NULL));
#define show(x) cout<<#x<<" = "<<x<<endl;
#define PQ(T) priority_queue<T,v(T),greater<T> >
#define bn(x) ((1<<x)-1)
#define dup(x,y) (((x)+(y)-1)/(y))
#define newline puts("")
#define v(T) vector<T>
#define vv(T) v(v(T))
using namespace std;
typedef long long int ll;
typedef unsigned uint;
typedef unsigned long long ull;
typedef pair<int,int> P;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<ll> vl;
typedef vector<P> vp;
inline int in() { int x; scanf("%d",&x); return x;}
template<typename T>inline istream& operator>>(istream&i,v(T)&v)
{rep(j,sz(v))i>>v[j];return i;}
template<typename T>string join(const v(T)&v)
{stringstream s;rep(i,sz(v))s<<' '<<v[i];return s.str().substr(1);}
template<typename T>inline ostream& operator<<(ostream&o,const v(T)&v)
{if(sz(v))o<<join(v);return o;}
template<typename T1,typename T2>inline istream& operator>>(istream&i,pair<T1,T2>&v)
{return i>>v.fi>>v.se;}
template<typename T1,typename T2>inline ostream& operator<<(ostream&o,const pair<T1,T2>&v)
{return o<<v.fi<<","<<v.se;}
template<typename T>inline ll suma(const v(T)& a) { ll res(0); for (auto&& x : a) res += x; return res;}
const double eps = 1e-10;
const ll LINF = 1001002003004005006ll;
const int INF = 1001001001;
#define dame { puts("-1"); return 0;}
#define yn {puts("YES");}else{puts("NO");}
const int MX = 200005;

// Union find
struct uf {
  vi d;
  uf(){}
  uf(int mx):d(mx,-1){}
  int root(int x) {
    if(d[x] < 0) return x;
    return d[x] = root(d[x]);
  }
  bool unite(int x, int y) {
    x = root(x); y = root(y);
    if(x == y) return false;
    // if(d[x] > d[y]) swap(x,y);
    d[x] += d[y]; d[y] = x;
    return true;
  }
  int size(int x) { return -d[root(x)];}
};
//

ll ans;
struct F {
  int z, t;
  F(int z=0, int t=0):z(z),t(t) {}
  bool operator<(const F& a) const {
    return (ll)z*a.t < (ll)a.z*t;
  }
  bool operator==(const F& a) const {
    return z==a.z && t==a.t;
  }
  F operator+(const F& a) const {
    ans += ll(t-z)*a.z;
    return F(z+a.z, t+a.t);
  }
};
typedef pair<F,int> FP;

int main() {
  int n;
  scanf("%d",&n);
  vi p(n,-1);
  rrep(i,n-1) {
    scanf("%d",&p[i]);
    --p[i];
  }
  v(F) x(n);
  rep(i,n) {
    int v;
    scanf("%d",&v);
    x[i] = F(!v,1);
  }

  F emp(-1,-1);
  uf t(n);
  priority_queue<FP> q;
  rrep(i,n-1) {
    q.push(FP(x[i],i));
  }
  while (sz(q)) {
    F nf = q.top().fi;
    int i = q.top().se;
    q.pop();
    if (!(x[i] == nf)) continue;
    int j = t.root(p[i]);
    x[j] = x[j]+x[i];
    x[i] = emp;
    t.unite(j,i);
    if (p[j] != -1) q.push(FP(x[j],j));
  }
  cout<<ans<<endl;
  return 0;
}






















Measured memory_bytes: 8052