#include<bits/stdc++.h>

 #define P pair<int,int>

 #define fir first

 #define sec second

 using namespace std;

 const int N=;

 vector<P> vec[N];

 bitset<N> bit[N];

 int n,f[*N],x,u,v,k;

 int find(int x){return x==f[x]?x:f[x]=find(f[x]);}

 void merge(int x,int y){f[find(x)]=find(y);}

 int main()

 {

     scanf("%d",&n);

     for (int i=;i<=n;i++)

     {

         scanf("%d",&k);

         while (k--) scanf("%d",&x),bit[x][i]=;

     }

     if (n==) return puts("1 2"),;

     for (int i=;i<=*n;i++) f[i]=i;

     for (int i=;i<=n;i++)

       for (int j=i+;j<=n;j++)

       {

           int cnt=(int)(bit[i]&bit[j]).count();

           if (cnt==) merge(i,j),merge(i+n,j+n);

           else if (cnt==) merge(i+n,j),merge(i,j+n);

           else vec[cnt].push_back(P(i,j));

       }

     if (vec[n].size()==n*(n-)/)//特判星

     {

         for (int i=;i<=n;i++) printf("1 %d\n",i);

         return ;

     }

     if (vec[n].size()==)//特判流星锤

     {

         printf("%d %d\n",u=vec[n][].fir,v=vec[n][].sec);

         for (int i=;i<=n;i++)

           if (i!=u&&i!=v) {merge(i,u),merge(i+n,u+n),merge(i+n,v),merge(i,v+n);break;}

         for (int i=;i<=n;i++)

           if (i!=u&&i!=v)

             if (find(i)==find(u)) printf("%d %d\n",i,u);else printf("%d %d\n",i,v);

         return ;

     }

     for (int i=n;i>=;i--)

       for (int j=;j<vec[i].size();j++)

         if (u=vec[i][j].fir,v=vec[i][j].sec,find(u)!=find(v))

         {

               printf("%d %d\n",u,v);

               merge(u+n,v);merge(u,v+n);

         }

     return ;

 }