#include<iostream>
#include<cstdio>
#include<cstring>
#define Mod 1000000007
using namespace std;
int n,a[100005],k[100005][12];
int haha(int s)
{
    if(a[s])return a[s];
    for(int i=1;i<=k[s][0];i++)
    {
        a[s]+=haha(k[s][i])%Mod;
        a[s]%=Mod;
    }
    return a[s];
}
int main()
{
    freopen("three_squirrels.in","r",stdin);
    freopen("three_squirrels.out","w",stdout);
    memset(a,0,sizeof(a));
    cin>>n;
    for(int i=1;i<=n;i++)
    {
        cin>>k[i][0];
        for(int j=1;j<=k[i][0];j++)
        {
            cin>>k[i][j];
        }
    }
    a[0]=1;
    haha(n);
    cout<<a[n];
}