#include<cstdio>
#include<vector>
#include<cstring>
#define N 100010
#define CK 1000000007
using namespace std;

int i,n,k,j,x;
int s[N],z[N],d[N];
vector <int> l[N];

inline int read(){
	int p=0,c=getchar();
	while (c<'0'||c>'9')	c=getchar();
	while (c>='0'&&c<='9')	p=p*10+c-48,c=getchar();
	return p;
}

inline void Work(){
	int i=0,t=1;
	z[++z[0]]=0;	s[0]=1;
	while (t<=z[0]){
		for (i=0;i<l[z[t]].size();i++){
			s[l[z[t]][i]]=(s[l[z[t]][i]]+s[z[t]])%CK;
			d[l[z[t]][i]]--;
			if (!d[l[z[t]][i]])	z[++z[0]]=l[z[t]][i];		
		}
		t++;
	}
	printf("%d\n",s[n]);
}

int main(){
	freopen("three_squirrels.in","r",stdin);
	freopen("three_squirrels.out","w",stdout);
	n=read();
	for (i=1;i<=n;i++){
		k=read();
		for (j=1;j<=k;j++){
			x=read();	l[x].push_back(i);	d[i]++;
		}
	}
	Work();
	return 0;
}