#include <iostream>
#include <cstdio>
#include <fstream>
#include <algorithm>
#include <vector>
#define MOD (1000000007)
//#define DEBUG_MODE

#ifdef DEBUG_MODE
using std::cin;
using std::cout;
#else
using std::ifstream;
using std::ofstream;
ifstream cin("three_squirrels.in");
ofstream cout("three_squirrels.out");
#endif
using std::endl;
using std::vector;

struct Package{
	int n;
	int pre;
	vector<int> ic;
	Package():n(0),pre(-1){
		
	}
};

Package * packs;
int n,m;

int calc(int pkg){
	if(packs[pkg].pre!=-1)
		return packs[pkg].pre;
	int r = 0;
	for(vector<int>::iterator it = packs[pkg].ic.begin();it!=packs[pkg].ic.end();it++){
		r += calc(*it);
		r %= MOD;
	}
	packs[pkg].pre = r;
	return r;
}

int main(int argc,char ** argv){
	int k,t;
	cin>>n;
	packs = new Package[n+1];
	for(int x=1;x<=n;x++){
		packs[x] = Package();
		packs[x].n = x;
		cin>>k;
		for(int y=0;y!=k;y++){
			cin>>t;
			packs[x].ic.push_back(t);
		}
	}
	packs[0].pre = 1;
	packs[0].n = 0;
	cout<<calc(n)<<endl;
	return 0;
}