#include<iostream>
#include<cstdio>
#include<vector>

#define mod 1000000007

const int maxn = 100000 + 100;

using namespace std;

int n;
int k;
int a;

int f[maxn]={0};

vector<int >A[maxn];

bool vis[maxn]={0};

inline void dfs(int x)
{
	vis[x]=true;
	for(int i=0;i<A[x].size();i++)
	{
		int t=A[x][i];
		if(!vis[t])
		{
			dfs(t);
		}
		f[x]=(f[x]+f[t])%mod;
	}
}

int main()
{
	freopen("three_squirrels.in","r",stdin);
	freopen("three_squirrels.out","w",stdout);
	scanf("%d",&n);
	for(int i=1;i<=n;i++)
	{
		scanf("%d",&k);
		for(int j=0;j<k;j++)
		{
			scanf("%d",&a);
			A[i].push_back(a);
		}
	}
	f[0]=1;
	vis[0]=true;
	dfs(n);
	cout<<f[n];
	return 0;
}