#include<cstdio>
#include<vector>
using namespace std;
const int maxn=100005,mod=1000000007;
int f[maxn];
bool vis[maxn];
int sz[maxn];
vector<int> content[maxn];
int dp(int x){
    if(vis[x])return f[x];
    f[x]=0;
    for(int i=0;i<sz[x];++i){
        f[x]=(f[x]+dp(content[x][i]))%mod;
    }
    vis[x]=true;return f[x];
}

int main(){
    freopen("three_squirrels.in","r",stdin);
    freopen("three_squirrels.out","w",stdout);
    int n;scanf("%d",&n);
    int x;
    for(int i=1;i<=n;++i){
        scanf("%d",&sz[i]);
        for(int j=1;j<=sz[i];++j){
            scanf("%d",&x);
            content[i].push_back(x);
        }
    }
    f[0]=1;vis[0]=true;
    printf("%d\n",dp(n));
    fclose(stdin);fclose(stdout);
    return 0;
}