#include <iostream>
#include <cstdio>
#include <queue>
#include <cstring>
using namespace std;
const int maxn=100000+10;
long long f[maxn];
int vis[maxn]={0};
queue<int>q;
const int XTT=1000000000+7;
struct Edge{
	int f,t,next;
	Edge(){
		next=0;
	}
}E[maxn*10];
int head[maxn]={0};
int edge=1;
inline void addedge(int x,int y){
	E[edge].f=x,E[edge].t=y,E[edge].next=head[x],head[x]=edge++;
}
inline void read(int &x){
	x=0;
	char c=getchar();
	bool flag=0;
	while(c<'0'||c>'9'){
		if(c=='-')
			flag=1;
		c=getchar();
	}
	while(c>='0'&&c<='9'){
		x=(x<<3)+(x<<1)+c-'0';
		c=getchar();
	}
	if(flag)
		x=-x;
}
int main(){
	freopen("three_squirrels.in","r",stdin);
	freopen("three_squirrels.out","w",stdout);
	int n,x;
	read(n);
	for(int i=1;i<=n;i++){
		read(vis[i]);
		for(int j=1;j<=vis[i];j++){
			read(x);
			addedge(x,i);
		}
	}
	f[0]=1;
	q.push(0);
	while(!q.empty()){
		int cd=q.front();
		q.pop();
		for(int i=head[cd];i;i=E[i].next){
			int u=E[i].t;
			vis[u]--;
			f[u]+=f[cd];
			if(f[u]>=XTT)
				f[u]-=XTT;
			if(!vis[u])
				q.push(u);
		}
	}
	printf("%lld\n",f[n]);
return 0;
}