#include<cstdio>
#include<cstring>
#include<cstdlib>
#include<string>
#include<set>
#include<map>
#include<queue>
#include<cmath>
#include<algorithm>
int n,i,f[100010],mo=1e9+7,a[100010][20],j,m[100010]; 
int dfs(int x){
	if(f[x])return f[x];
	for(int i=1;i<=m[x];i++){
		f[x]+=dfs(a[x][i]);
		if(f[x]>=mo)f[x]-=mo;
	}
	return f[x];
}
int main(){
	freopen("three_squirrels.in","r",stdin);
	freopen("three_squirrels.out","w",stdout);
	scanf("%d",&n);
	for(i=1;i<=n;i++){
		scanf("%d",m+i);
		for(j=1;j<=m[i];j++)scanf("%d",a[i]+j);
	}
	f[0]=1;
	for(i=1;i<n;i++)f[i]=dfs(i);
	printf("%d",dfs(n));
	return 0;
}