#include<cstdio>
#include<cstring>
#define Cu fclose(stdin);fclose(stdout);return 0;
#define Begin freopen("three_squirrels.in","r",stdin);freopen("three_squirrels.out","w",stdout);chul();Cu;
using namespace std;
const int maxn=100010;
int f[maxn],head[maxn],tim,p=1000000000+7;
struct op{
	int to,next;
}r[maxn*10];
int dfs(int x){
	if(f[x]!=-1)return f[x];
	f[x]=0;
	int y;
	for(int i=head[x];i;i=r[i].next){
		y=r[i].to;
		f[x]=(f[x]+dfs(y))%p;
	}
	return f[x];
}
void insert(int fr,int to){
	tim++;
	r[tim].to=to;
	r[tim].next=head[fr];
	head[fr]=tim;
}
void chul(){
	memset(f,-1,sizeof(f));
	f[0]=1;
	int n,m,x;
	scanf("%d",&n);
	for(int i=1;i<=n;i++){
		scanf("%d",&m);
		for(int j=0;j<m;j++){
			scanf("%d",&x);
			insert(i,x);
		}
	}
	printf("%d\n",dfs(n));
}
int main(){
	Begin;
}