#include<cstdio>
#include<cstring>
#define FILE "three_squirrels"
namespace IO{
	char buf[1<<15],*fs,*ft;
	inline char gc(){return (fs==ft&&(ft=(fs=buf)+fread(buf,1,1<<15,stdin),fs==ft))?0:*fs++;}
	inline int read(){
		int x=0,rev=0,ch=gc();
		while(ch<'0'||ch>'9'){if(ch=='-')rev=1;ch=gc();}
		while(ch>='0'&&ch<='9'){x=(x<<1)+(x<<3)+ch-'0';ch=gc();}
		return rev?-x:x;
	}
}using namespace IO;
const int MAXN(1000005),P(int(1e9)+7);
int n,g[MAXN][11];
int f[MAXN];
int F(int x){
	if(f[x]==-1){
		f[x]=0;
		for(int i=1;i<=g[x][0];i++)
			if((f[x]+=F(g[x][i]))>=P)
				f[x]-=P;
	}
	return f[x];
}

int main(){
	freopen(FILE".in","r",stdin);
	freopen(FILE".out","w",stdout);
	n=read();
	memset(f,-1,sizeof f);
	f[0]=1;
	for(int i=1,j;i<=n;i++)
		for(g[i][0]=read(),j=1;j<=g[i][0];j++)
			g[i][j]=read();
	printf("%d\n",F(n));
	return 0;
}