#include<iostream>
#include<cstdio>
#define maxn 100010
#define mod 1000000007
#define ll long long
using namespace std;
ll n,num,head[maxn],c[maxn];
struct node{
	ll v,pre;
}e[maxn*10];
ll init(){
	ll x=0,f=1;char s=getchar();
	while(s<'0'||s>'9'){if(s=='0')f=-1;s=getchar();}
	while(s>='0'&&s<='9'){x=x*10+s-'0';s=getchar();}
	return x*f;
}
void Add(ll from,ll to){
	num++;e[num].v=to;
	e[num].pre=head[from];
	head[from]=num;
}
ll Dfs(ll x){
	if(c[x])return c[x];
	for(int i=head[x];i;i=e[i].pre){
		ll v=e[i].v;
		c[x]+=Dfs(v);c[x]%=mod;
	}
	return c[x];
}
int main()
{
	freopen("three_squirrels.in","r",stdin);
	freopen("three_squirrels.out","w",stdout);
	n=init();
	ll x,y;c[0]=1;
	for(int i=1;i<=n;i++){
		x=init();
		while(x--){
			y=init();Add(i,y);
		}
	}
	cout<<Dfs(n)<<endl;
	return 0;
}