#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cmath>
using namespace std;
int n,m;
const long long a=1000000007;
long long ans[100001];
int x;
int main()
{
	freopen("three_squirrels.in","r",stdin);
	freopen("three_squirrels.out","w",stdout);
	cin>>n;
	ans[0]=1;
	for(int i=1;i<=n;i++)
	{
		scanf("%d",&m);
		for(int j=1;j<=m;j++)
		{
			scanf("%d",&x);
			ans[i]+=ans[x]%a;
		}
	}
	cout<<ans[n]<<endl;
	return 0;
}