#include<cstring>
#include<cstdio>
#include<algorithm>
#include<iostream>
using namespace std;
const int maxn=100010;
int head[maxn],n,len,f[maxn],mod=1000000007;
struct Edge
{
	int to,next;
}e[maxn*2];
int memory(int);
void Insert(int,int);
int main()
{
	freopen("three_squirrels.in","r",stdin);
	freopen("three_squirrels.out","w",stdout);
	memset(head,-1,sizeof(head));
	scanf("%d",&n);f[0]=1;
	for(int i=1;i<=n;i++)
	{
		int num;scanf("%d",&num);
		for(int j=1;j<=num;j++)
		{
			int x;scanf("%d",&x);
			Insert(i,x);
		}
	}
	int ans=memory(n);
	printf("%d\n",ans);
	fclose(stdin);
	fclose(stdout);
	//system("pause");
	return 0;
}
void Insert(int x,int y)
{
	len++;e[len].to=y;
	e[len].next=head[x];head[x]=len;
}
int memory(int x)
{
	if(f[x])return f[x];
	for(int i=head[x];i!=-1;i=e[i].next)
	{
		int j=e[i].to;
		f[x]+=memory(j);f[x]%=mod;
	}
	return f[x];
}