#include<cstdio>
#include<cstring>
#include<algorithm>
#define LL long long
using namespace std;
const int maxn=100010;
const LL p=1000000007ll;
namespace mine{
	template<class T>inline void readint(T &__x){
		static int __c;
		//static bool __neg;
		__x=0;
		//__neg=false;
		do __c=getchar();while(__c==' '||__c=='\n'||__c=='\r'||__c=='\t');
		/*if(__c=='-'){
			__neg=true;
			__c=getchar();
		}*/
		for(;__c>='0'&&__c<='9';__c=getchar())__x=__x*10+(__c^48);
		//if(__neg)__x=-__x;
	}
	template<class T>inline void putint(T __x){
		static int __a[40],__i,__j;
		//static bool __neg;
		//__neg=__x<0;
		//if(__neg)__x=-__x;
		__i=0;
		do{
			__a[__i++]=__x%(T)10^(T)48;
			__x/=10;
		}while(__x);
		//if(__neg)putchar('-');
		for(__j=__i-1;__j^-1;__j--)putchar(__a[__j]);
	}
}
using namespace mine;
struct edge{
	int to,prev;
}e[maxn<<1];
void insert(int,int);
void dfs(int);
LL ans=0ll;
int n,len=0,last[maxn]={0},prt[maxn]={0},x,y;
LL w[maxn],sum[maxn];
int main(){
#define MINE
#ifdef MINE
	freopen("asm_algo.in","r",stdin);
	freopen("asm_algo.out","w",stdout);
#endif
	readint(n);
	readint(w[1]);
	for(int i=2;i<=n;i++){
		readint(prt[i]);
		readint(w[i]);
		insert(prt[i],i);
	}
	dfs(1);
	ans<<=1;
	for(int i=1;i<=n;i++)ans=(ans+w[i]*w[i]%p*w[i]%p)%p;
	putint(ans);
#ifndef MINE
	printf("\n--------------------DONE--------------------\n");
	for(;;);
#endif
	return 0;
}
void insert(int x,int y){
	e[++len].to=y;
	e[len].prev=last[x];
	last[x]=len;
}
void dfs(int x){
	sum[x]=w[x];
	for(int i=last[x];i;i=e[i].prev){
		dfs(e[i].to);
		ans=(ans+(LL)sum[x]*(LL)sum[e[i].to]%p*(LL)w[x]%p)%p;
		sum[x]=(sum[x]+sum[e[i].to])%p;
	}
}