#include<iostream>
#include<cstdio>
#include<cstring>
#include<cstdlib>
#include<string>
#include<algorithm>
#include<ctime>
#include<cmath>
#include<queue>
using namespace std;
#define FILE "three_squirrels"
#define pii pair<long long,long long>
#define LL long long 
#define up(i,j,n) for(int i=j;i<=n;i++)
#define down(i,n,j) for(int i=n;i>=j;i--)
#define max(x,y) ((x)>(y)?(x):(y))
#define min(x,y) ((x)<(y)?(x):(y))
#define abs(x) ((x)<0?(-(x)):(x))
template<typename T>inline bool chkmax(T &a,T b){return a<b?a=b,true : false;}
template<typename T>inline bool chkmin(T &a,T b){return a>b?a=b,true : false;}
int read(){
	int x=0;char ch=getchar();bool flag=0;
	while(ch<'0'||ch>'9'){if(ch=='-')flag=1;ch=getchar();}
	while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();}
	return flag?-x:x;
}
namespace OI{
	const int maxn=101000,mod=1000000007;
	int f[maxn];
	int n;
	struct node{
		int y,next;
	}e[2010000];
	int len=0,linkk[maxn];
	void insert(int x,int y){
		e[++len].y=y;
		e[len].next=linkk[x];
		linkk[x]=len;
	}
	int dfs(int x){
		if(f[x]!=-1)return f[x];
		f[x]=0;
		for(int i=linkk[x];i;i=e[i].next)f[x]=(f[x]+dfs(e[i].y))%mod;
		return f[x];
	}
	void slove(){
		memset(f,-1,sizeof(f));
		f[0]=1;
		n=read();int k,x;
		up(i,1,n){
			k=read();
			up(j,1,k){
				x=read();
				insert(i,x);
			}
		}
		printf("%d\n",dfs(n));
	}
}

int main(){
	freopen(FILE".in","r",stdin);
	freopen(FILE".out","w",stdout);
	using namespace OI;
	slove();
	return 0;
}