#include<iostream>
#include<cstdio>
#include<cstring>
#include<cstdlib>
#define pa system("pause")
using namespace std;
const int maxn=101000;
typedef long long LL;
struct edge
{
 	int to,next;
}e[maxn<<1];
int n,m,len,head[maxn],mod=1000000007;
void insert(int x,int y)
{
	e[++len].to=y;e[len].next=head[x];head[x]=len;
}
LL dfs(int x)
{
	if(x==0)return 1; LL tot=0;
	for(int i=head[x];i;i=e[i].next)
	{
		int k=e[i].to;
		tot+=dfs(k);tot%=mod;
	}
	return tot%mod;
}
int main()
{
	freopen("three_squirrels.in","r",stdin);
	freopen("three_squirrels.out","w",stdout);
	scanf("%d",&n);
	for(int i=1;i<=n;++i)
	{
		int x,y;
		scanf("%d",&x);
		for(int j=1;j<=x;++j)
		{
			scanf("%d",&y);
			insert(i,y);//insert(y,i);
		} 
	}
	printf("%lld\n",dfs(n));
	fclose(stdin);
	fclose(stdout);
	return 0; 
}