1 #include<iostream>
  2 #include<cstdio>
  3 #include<cstring>
  4 #include<string>
  5 #include<algorithm>
  6 #include<vector>
  7 #include<cmath>
  8 #include<stack>
  9 #include<queue>
 10 #define MAXN 3101
 11 #define ll long long
 12 using namespace std;
 13 const ll mod=1e9+7;
 14 struct node{ll to,n;}e[MAXN];
 15 ll head[MAXN],tot;
 16 void add(ll u,ll v){e[++tot].to=v;e[tot].n=head[u];head[u]=tot;}
 17 ll size[MAXN];
 18 ll f[MAXN][MAXN],g[MAXN],h[MAXN];
 19 ll n;ll chu[MAXN];
 20 ll pow(ll x,ll y)
 21 {
 22     ll ans=1;
 23     while(y)
 24     {
 25        if(y&1)ans=(ans*x)%mod;
 26        x=(x*x)%mod;
 27        y>>=1;
 28     }
 29     return ans%mod;
 30 }
 31 void DFS(ll x)
 32 {
 33    size[x]=1;
 34    for(ll i=head[x];i;i=e[i].n)
 35    {
 36        ll to=e[i].to;
 37        DFS(to);
 38        size[x]+=size[to];
 39    }
 40    ll ppow=pow(chu[x],mod-2ll)%mod;
 41    for(ll i=head[x];i;i=e[i].n)
 42    {
 43        for(ll i=0;i<=size[x]+1;++i)g[i]=1;
 44        for(ll j=head[x];j;j=e[j].n)
 45        {
 46            ll fs,gs;
 47            ll to1=e[i].to;ll to2=e[j].to;
 48            for(ll k=0;k<=size[to2]+1;++k)
 49            {
 50                if(to1==to2){
 51                    if(!k)fs=f[to2][k];else fs=f[to2][k]-f[to2][k-1];
 52                    if(!k)gs=g[k];     else gs=g[k]-g[k-1];
 53                    h[k]=(fs*g[k]%mod+gs*f[to2][k]%mod-gs*fs+mod)%mod;
 54          //          printf("h[%lld]=%lld\n",k,h[k]);
 55                }
 56                else if(k){
 57                    if(!k)fs=f[to2][k-1];else fs=f[to2][k-1]-f[to2][k-2];
 58                    if(!k)gs=g[k];       else gs=g[k]-g[k-1];
 59                    h[k]=(fs*g[k]%mod+gs*f[to2][k-1]%mod-gs*fs+mod)%mod;
 60                }
 61            }
 62            g[0]=h[0];h[0]=0;
 63            for(ll k=1;k<=size[to2]+1;++k)
 64            {
 65                g[k]=(g[k-1]+h[k])%mod;h[k]=0;
 66            }
 67        }
 68        for(ll j=size[x]+1;j>=1;--j)
 69        {
 70            g[j]=(g[j]-g[j-1]+mod)%mod;//printf("g[%lld]=%lld\n",j,g[j]);
 71        }
 72        for(ll j=0;j<=size[x]+1;++j)
 73        {
 74            f[x][j]=(f[x][j]+g[j]*ppow%mod)%mod;
 75        //  printf("f[%lld][%lld]=%lld\n",x,j,f[x][j]);
 76        }
 77        // printf("p=%lld\n",pow(chu[x],mod-2ll));
 78    }
 79    if(head[x]==0)f[x][0]=1;
 80    for(ll i=1;i<=size[x]+1;++i)
 81    {
 82         f[x][i]=(f[x][i]+f[x][i-1]+mod)%mod;
 83        // printf("f[%lld][%lld]=%lld\n",x,i,f[x][i]);
 84    }
 85 }
 86 ll ru[MAXN];ll si=1;
 87 int main()
 88 {
 89      scanf("%lld",&n);
 90      for(ll i=1;i<=n;++i){
 91         scanf("%lld",&chu[i]);
 92         for(ll j=1;j<=chu[i];++j){
 93             ll y;
 94             scanf("%lld",&y);
 95             add(i,y);ru[y]++;
 96         }
 97      }
 98      ll root=0;
 99      for(ll i=1;i<=n;++i){
100         if(ru[i]==0)
101          root=i;
102      }
103      DFS(root);
104      ll ans=0;
105      for(ll i=1;i<=size[root]+1;++i)
106      {
107          ans=(ans+i*(f[root][i]-f[root][i-1]%mod)+mod)%mod;
108      }
109      printf("%lld\n",(ans+mod)%mod);
110 }