#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<cmath>
#include<queue>
#define maxn 100100
using namespace std;
const int mod=1000000007;
int n;
int ind[maxn],w[maxn];
struct Edge{
	int to,next,w;
}e[maxn*10];
int head[maxn],tot;
void Add(int from,int to)
{
	e[++tot].to=to;
	e[tot].next=head[from];
	head[from]=tot;
}
queue<int> q;
void Topology()
{
	while(!q.empty()){
		int x=q.front();q.pop();
		for(int i=head[x];i!=-1;i=e[i].next){
			int to=e[i].to;
			ind[to]--;
			if(ind[to]==0)q.push(to);
			w[to]+=w[x];w[to]%=mod;
		}
	}
}
int main()
{
	freopen("three_squirrels.in","r",stdin);
	freopen("three_squirrels.out","w",stdout);
	memset(head,-1,sizeof(head));
	w[0]=1;q.push(0);
	scanf("%d",&n);
	int k,x;
	for(int i=1;i<=n;i++){
		scanf("%d",&ind[i]);
		for(int j=1;j<=ind[i];j++){
			scanf("%d",&x);
			Add(x,i);
		}
	}
	Topology();
	printf("%d\n",w[n]);
	fclose(stdin);fclose(stdout);
	return 0;
}