#include<iostream>
#include<cstdio>
#include<cstdlib>
using namespace std;
#define ll long long
int read()
{
    int x,f=1;
    char ch;
    while(ch=getchar(),!isdigit(ch))if(ch=='-')f=-1;
    x=ch-48;
    while(ch=getchar(),isdigit(ch))x=x*10+ch-48;
    return x*f;
}
void write(ll x)
{
	if(x<0)putchar('-'),x=-x;
	int cnt=0;char ch[50];
	while(ch[++cnt]=x%10+48,x/=10);
	while(putchar(ch[cnt]),--cnt);
	putchar('\n');
}
#define maxe 1000100
#define maxn 100100
struct edge
{
	int n,t;
}a[maxe];
int len,head[maxn];
ll f[maxn],mod=1000000007;
void insert(int x,int y)
{
	a[++len].t=y;a[len].n=head[x];head[x]=len;
}
#define k a[i].t
void dfs(int x)
{
	for(int i=head[x];i;i=a[i].n)
	{
		if(f[k])f[x]+=f[k],f[x]%=mod;
		else
		{
			dfs(k);
			f[x]+=f[k];
			f[x]%=mod;
		}
	}
}
#undef k 
int main()
{
	freopen("three_squirrels.in","r",stdin);
	freopen("three_squirrels.out","w",stdout);
	int n=read();
	for(int i=1;i<=n;i++)
	{
		int k=read(),y;
		for(int j=1;j<=k;j++)y=read(),insert(i,y);
	}
	f[0]=1;
	dfs(n);
	write(f[n]);
//	system("pause");
	fclose(stdin);
	fclose(stdout);
}