#include<iostream>
#include<cstdio>
#include<cstring>
#define maxn 100010
#define mod 1000000007
using namespace std;
int n,topt;
int first[maxn],f[maxn];
struct edge
{
	int to;
	int next;
}e[maxn*10];
void add(int x,int y)
{
	topt++;
	e[topt].to=y;
	e[topt].next=first[x];
	first[x]=topt;
}
int dfs(int now)
{
	if(f[now]!=-1)return f[now];
	if(now==0)return f[now]=1;
	int sum=0;
	for(int i=first[now];i;i=e[i].next)
	{
		int to=e[i].to;
		sum+=dfs(to);
		sum%=mod;
	}
	return f[now]=sum;
}
int main()
{
	freopen("three_squirrels.in","r",stdin);
	freopen("three_squirrels.out","w",stdout);
	int i,j,k;
	scanf("%d",&n);
	for(i=1;i<=n;i++)
	{
		int x,y;
		scanf("%d",&y);
		for(j=1;j<=y;j++)
		{
			scanf("%d",&x);
			add(i,x);
		}
	}
	memset(f,-1,sizeof(f));
	printf("%d\n",dfs(n));
	return 0;
}