#include <bits/stdc++.h>
using namespace std;
inline int read() {
  int x = 0, f = 1;
  char ch = getchar();
  while (ch < '0' || ch > '9') {
    if (ch == '-') f = -1;
    ch = getchar();
  }
  while (ch >= '0' && ch <= '9') {
    x = x * 10 + ch - '0';
    ch = getchar();
  }
  return x * f;
}
const int N = 1e3 + 7;
const int INF = 0x7f7f7f7f;
bitset<N> G[N], S[N], nl;
int n, fa[N];
int find(int x) {
  if (fa[x] != x)
    return fa[x] = find(fa[x]);
  else
    return fa[x];
}
int main() {
  n = read();
  for (int i = 1; i <= n; i++) {
    int k = read();
    while (k--) {
      int x = read();
      G[i][x] = 1;
    }
  }
  for (int i = 1; i <= n; i++) fa[i] = i;
  bitset<N> t;
  int x, y, cnt = 0;
  for (int i = 1; i <= n; i++)
    for (int j = 1; j <= n; j++) {
      if (i == j) continue;
      t = (G[i] & G[j]);
      if (t.count() == 2) {
        x = 0, y = 0;
        for (int k = 1; k <= n; k++)
          if (t[k]) (!x) ? (x = k) : (y = k);
        int dx = find(x), dy = find(y);
        if (dx != dy) {
          fa[dx] = dy;
          printf("%d %d\n", x, y);
          cnt++;
          S[x][x] = S[y][y] = S[x][y] = S[y][x] = 1;
          nl[x] = nl[y] = 1;
        }
      }
    }
  if (cnt == 0) {
    for (int i = 2; i <= n; i++) printf("%d %d\n", 1, i);
    return 0;
  } else if (cnt == 1) {
    for (int i = 1; i <= n; i++) {
      if (G[i].count() < n) {
        for (int j = 1; j <= n; j++)
          if (!nl[j]) printf("%d %d\n", (G[i][j] ? x : y), j);
        break;
      }
    }
    return 0;
  }
  for (int i = 1; i <= n; i++)
    if (!nl[i]) {
      int mn = INF;
      for (int j = 1; j <= n; j++)
        if (G[j][i] && (G[j] & nl).count() < mn)
          t = (G[j] & nl), mn = t.count();
      for (int j = 1; j <= n; j++)
        if (t[j] && S[j] == t) {
          printf("%d %d\n", i, j);
          break;
        }
    }
  return 0;
}
