#include<bits/stdc++.h>
#define int long long
#define rep(i,a,b) for(int i=a;i<=b;i++)
#define rop(i,a,b) for(int i=a;i<b;i++)
#define per(i,a,b) for(int i=a;i>=b;i--)
#define por(i,a,b) for(int i=a;i>b;i--)
#define endl '\n'
#define pii pair<int,int>
#define fi first
#define se second
typedef long long ll;
typedef unsigned long long ull;
typedef double lf;
typedef long double ld;
using namespace std;
int n,a[100005],b[100005],c[100005],ch[100005][2];
struct node{
    int ans,ans1,ans2,sum;
    node operator+(const node&x)const{
        return(node){ans+x.ans,ans1+x.ans1,ans2+x.ans2,sum+x.sum};
    }
    bool operator<(const node&x)const{
		return ans<x.ans;
	}
}x[100005];
void dfs(int u){
    if(u>n){
        u-=n;
        x[u+n]={1ll*c[u]*a[u]*b[u],1ll*c[u]*b[u],1ll*c[u]*a[u],c[u]};
        return;
    }
    dfs(ch[u][0]);
	dfs(ch[u][1]);
    node r=x[ch[u][1]];
	r.ans+=r.ans2;
	r.ans1+=r.sum;
    node l=x[ch[u][0]];
	l.ans+=l.ans1;
	l.ans2+=l.sum;
    x[u]=min(l+x[ch[u][1]],r+x[ch[u][0]]);
}
signed main(){
	ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
	cin>>n;
    rop(i,1,n){
        cin>>ch[i][0]>>ch[i][1];
        if(ch[i][0]<0)
			ch[i][0]=n-ch[i][0];
        if(ch[i][1]<0)
			ch[i][1]=n-ch[i][1];
    }
    rep(i,1,n)
		cin>>a[i]>>b[i]>>c[i];
    dfs(1);
    cout<<x[1].ans;
	return 0;
}
/*
？现在jc方式那么低级啊
*/

https://www.luogu.com.cn/record/169316248