#include <queue>
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;

#define maxn 100010
#define mod 1000000007

int du[maxn];
int tot, head[maxn];
int cnt[maxn];
queue <int> q;

struct Edge{
	int to, nx;
}e[maxn*12];

void edge(int u,int v){
	e[++tot].to = v;
	e[tot].nx = head[u];
	head[u] = tot;
}

void Topo(){
	while(!q.empty()){
		int x = q.front();q.pop();
		for(int i = head[x];i;i = e[i].nx){
			int to = e[i].to;
			cnt[to] = (cnt[to]+cnt[x])%mod;du[to]--;
			if(!du[to]) q.push(to);
		}
	}
}

int main(){
	freopen("three_squirrels.in","r",stdin);
	freopen("three_squirrels.out","w",stdout);
	int n;scanf("%d",&n);
	cnt[0] = 1;
	for(int i = 1,k,a;i <= n;i ++){
		scanf("%d",&k);
		for(int j = 1;j <= k;j ++){
			scanf("%d",&a);edge(a,i);
			du[i]++;
		}
	}
	for(int i = 0;i <= n;i ++) if(!du[i]) q.push(i);
	Topo();
	printf("%d\n",cnt[n]);
	getchar();getchar();
	return 0;
}