#include <cstdio>
#include <algorithm>
using namespace std;
const int maxn = 5e5 + 5;
int n, m;
int tot, head[maxn], ver[maxn], nxt[maxn];
long long weigh[maxn], edge[maxn];
void add(int u, int v, long long w) {
    ver[++tot] = v, edge[tot] = w, nxt[tot] = head[u], head[u] = tot;
}
long long W[maxn], S[maxn], T[maxn], dp[maxn];
int cnt, son[maxn];
bool cmp(const int &x, const int &y) {
    return W[x] * (S[y] + T[y]) > W[y] * (S[x] + T[x]);
}
void dfs(int u) {
    W[u] = weigh[u], S[u] = 0;
    for (int i = head[u]; i; i = nxt[i]) {
        int v = ver[i]; long long w = edge[i];
        dfs(v);
        T[v] = w, W[u] += W[v], S[u] += S[v] + w;
    }
    cnt = 0;
    for (int i = head[u]; i; i = nxt[i]) son[++cnt] = ver[i];
    sort(son + 1, son + cnt + 1, cmp);
    long long tim = 0;
    dp[u] = 0;
    for (int i = 1; i <= cnt; i++) {
        dp[u] += (tim + T[son[i]]) * W[son[i]] + dp[son[i]];
        tim += S[son[i]] + T[son[i]];
    }
    return;
}
int main() {
    scanf("%d", &n);
    for (int v = 2, u; v <= n; v++) {
        long long w; scanf("%d%lld", &u, &w);
        add(u, v, w);
    }
    for (int i = 1; i <= n; i++) scanf("%lld", weigh + i);
    dfs(1);
    printf("%lld\n", dp[1]);
    return 0;
}