#include<bits/stdc++.h>
//A-随机游走
using namespace std;
typedef long long ll;

int res;
char ch;
int read()
{
    res = 0, ch = getchar();
    while (ch == ' ' || ch == '\n')
        ch = getchar();
    while (ch >= '0' && ch <= '9')
        res = (res << 3) + (res << 1) + (ch ^ 48), ch = getchar();
    return res;
}
int n;
int f, w;
struct Edge{
    int ed, ti;
};
struct Tree{
    int wi;
    int wiSum, tiSum;
    double im;//重要程度。= tiSum / wiSum
    vector<Edge> ei;
}T[500005];
bool cmp(Edge xi, Edge yi)
{
    return T[xi.ed].im < T[yi.ed].im;
}
void dfs(int rt)
{
    //printf("#%d\n", rt);
    for (int i = 0;i < T[rt].ei.size(); ++i)
        T[T[rt].ei[i].ed].tiSum += T[rt].ei[i].ti,
        dfs(T[rt].ei[i].ed), 
        T[rt].wiSum += T[T[rt].ei[i].ed].wiSum, 
        T[rt].tiSum += T[T[rt].ei[i].ed].tiSum;
    T[rt].wiSum += T[rt].wi;
    T[rt].im = (double)T[rt].tiSum / T[rt].wiSum;
    sort(T[rt].ei.begin(), T[rt].ei.end(), cmp);
}
ll ans, tcnt;
void dfs_FindAns(int rt)
{
    ans += T[rt].wi * tcnt;
    //printf("#%d: %d, %lld\n", rt, T[rt].wi, tcnt);
    for (int i = 0;i < T[rt].ei.size(); ++i)
        tcnt += T[rt].ei[i].ti, dfs_FindAns(T[rt].ei[i].ed); 
}
int main()
{
    //freopen("ex_walk3.in", "r", stdin);
    n = read();
    for (int i = 2;i <= n; ++i)
        f = read(), w = read(), T[f].ei.push_back({i, w});
    for (int i = 1;i <= n; ++i)
        T[i].wi = read();
    dfs(1);
    dfs_FindAns(1);
    printf("%lld", ans);
    return 0;
}