#include<cstdio>
#include<iostream>
#include<algorithm>
#include<vector>
using namespace std;
const int maxn=100000+10;
const int mod=1000000007;
int f[maxn];
vector<int> e[maxn];
int n;
int dfs(int x){
	if(f[x]) return f[x];
	int cnt=0;
	for(int i=0;i<e[x].size();i++){
		if(e[x][i]==0) cnt++;
		else
		cnt=(cnt+dfs(e[x][i]))%mod;
	}
	return f[x]=cnt;
}

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