#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
const int maxn=100010;
struct Edge{ int to,next; }e[maxn];
int val[maxn],head[maxn],len,mod=1000000007;
void Insert(int x,int y){
	len++;
	e[len].to=y; e[len].next=head[x];
	head[x]=len;
}
int Dp(int x){
	if(val[x]) return val[x];
	for(int i=head[x];i;i=e[i].next){
		int j=e[i].to;
		val[x]+=Dp(j); val[x]%=mod;
	}
	return val[x]%mod;
}
int main(){
	freopen("three_squirrels.in","r",stdin);
	freopen("three_squirrels.out","w",stdout);
	int n;scanf("%d",&n);
	for(int i=1;i<=n;i++){
		int x;scanf("%d",&x);
		for(int j=1;j<=x;j++){
			int y;scanf("%d",&y);
			Insert(i,y);
		}
	}
	val[0]=1; printf("%d\n",Dp(n));
	return 0;
}
/*
6
1 5
1 1
5 2 1 5 4 0
1 0
1 4
2 3 2

6
1 0
3 1 3 0
2 0 4
1 0
4 1 2 3 4
1 5
 */