#include <bits/stdc++.h>
using namespace std;
inline long long read() {
  long long x(0), neg(1);
  char ch(getchar());
  while (!isdigit(ch)) {
    if (ch == '-') neg = -1;
    ch = getchar();
  }
  while (isdigit(ch)) {
    x = (x << 1) + (x << 3) + (ch ^ 48);
    ch = getchar();
  }
  return x * neg;
}
const long long maxn = 1000;
bitset<maxn + 5> a[maxn + 5], p, edge[maxn + 5], unleaf;
bitset<maxn + 5> ans;
long long cnt;
long long fa[maxn + 5];
inline long long find(long long x) {
  if (x == fa[x]) return x;
  return fa[x] = find(fa[x]);
}
signed main() {
  long long n = read();
  for (long long i = 1; i <= n; ++i) {
    long long x(read());
    for (long long j = 1; j <= x; ++j) {
      long long xx = read();
      a[i][xx] = 1;
    }
  }
  for (long long i = 1; i <= n; ++i) fa[i] = i;
  long long u, v;
  for (long long i = 1; i <= n; ++i) {
    for (long long j = 1; j <= n; ++j) {
      p = (a[i] & a[j]);
      if (p.count() == 2) {
        u = 0, v = 0;
        for (long long k = 1; k <= n; ++k) {
          if (p[k]) {
            (!u) ? (u = k) : (v = k);
          }
        }
        long long fu(find(u)), fv(find(v));
        if (fu != fv) {
          fa[fu] = fv;
          printf("%lld %lld\n", u, v);
          ++cnt;
          edge[u][u] = edge[v][v] = edge[u][v] = edge[v][u] = 1;
          unleaf[u] = unleaf[v] = 1;
        }
      }
    }
  }
  if (cnt == 0) {
    for (long long i = 2; i <= n; ++i) {
      printf("1 %lld\n", i);
    }
    return 0;
  } else if (cnt == 1) {
    for (long long i = 1; i <= n; ++i) {
      if (a[i].count() < n) {
        for (long long j = 1; j <= n; ++j) {
          if (!unleaf[j]) {
            printf("%lld %lld\n", a[i][j] ? u : v, j);
          }
        }
        break;
      }
    }
    return 0;
  }
  for (long long i = 1; i <= n; ++i) {
    if (!unleaf[i]) {
      long long minv(2147483647);
      for (long long j = 1; j <= n; ++j) {
        if (a[j][i] && (a[j] & unleaf).count() < minv) {
          ans = (a[j] & unleaf);
          minv = ans.count();
        }
      }
      for (long long j = 1; j <= n; ++j) {
        if (ans[j] && edge[j] == ans) {
          printf("%lld %lld\n", i, j);
          break;
        }
      }
    }
  }
  return 0;
}
