#include<bits/stdc++.h>

namespace IO
{
	template<typename Type>
	void read(Type &x){
		char ch=getchar();
		x=0;bool f=0;
		while(ch<'0'||ch>'9')
			f|=(ch=='-'),ch=getchar();
		while(ch>='0'&&ch<='9')
			x=((x<<1)+(x<<3)+(ch^48)),ch=getchar();
		x=f?-x:x;
	}
}

using namespace std;

#define N 500005
#define LL long long

int n,w;
int val[N],fa[N];
LL nowtime,ans;

bool opt1=true,opt2=true;

struct node
{
	int v,w;
	bool operator < (const node &a) const
	{
		return 1ll*w*val[a.v]<1ll*a.w*val[v];
	}
};

vector<node> Graph[N];

void dfs(int u)
{
	ans+=(nowtime*val[u]);
	for(int i=0;i<Graph[u].size();i++)
		dfs(Graph[u][i].v);
}

int main()
{
	IO::read(n);
	for(int i=2;i<=n;i++){
		IO::read(fa[i]);IO::read(w);
		Graph[fa[i]].push_back({i,w});
	}	
	for(int i=1;i<=n;i++)
		IO::read(val[i]);
	for(int i=1;i<=n;i++)
		sort(Graph[i].begin(),Graph[i].end());		
	dfs(1);
	printf("%lld",ans);
	return 0;
}