//紫萱的电脑旁真的就放了个森林大禮包……
#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cstring>
#include<cmath>
using namespace std;
const long long mo=1000000007;
int read(){int z=0,mark=1;  char ch=getchar();
	while(ch<'0'||ch>'9'){if(ch=='-')mark=-1;  ch=getchar();}
	while(ch>='0'&&ch<='9'){z=(z<<3)+(z<<1)+ch-'0';  ch=getchar();}
	return z*mark;
}
struct ddd{int next,y;}e[1100000];int LINK[110000],ltop=0;
inline void insert(int x,int y){e[++ltop].next=LINK[x];LINK[x]=ltop;e[ltop].y=y;} 
int n;
long long ge[110000];
void dfs(int x){
	for(int i=LINK[x];i;i=e[i].next){
		if(!ge[e[i].y])  dfs(e[i].y);
		ge[x]=(ge[x]+ge[e[i].y])%mo;
	}
}
int main(){
	//freopen("ddd.in","r",stdin);
	freopen("three_squirrels.in","r",stdin);
	freopen("three_squirrels.out","w",stdout);
	cin>>n;
	int _ge,_child;
	for(int i=1;i<=n;i++){
		ge[i]=0;
		_ge=read();
		while(_ge --> 0){//趋向于
			_child=read();
			insert(i,_child);
		}
	}
	ge[0]=1;
	dfs(n);
	cout<<ge[n]<<endl;
	return 0;
}