public void solve() throws IOException {
    int T = nextInt();
    for (int t = 1; t <= T; t++) {
      int N = nextInt();
      int[] counts = new int[2500];
      
      for (int i = 0; i < 2 * N - 1; i++) {
        for (int j = 0; j < N; j++) {
          int e = nextInt();
          counts[e - 1]++;
        }
      }
      
      List<Integer> line = new ArrayList<Integer>(N);
      for (int i = 0; i < 2500; i++) {
        if (counts[i] % 2 != 0) {
          line.add(i + 1);
        }
      }
      Collections.sort(line);
      
      StringBuilder sb = new StringBuilder();
      for (int i = 0; i < line.size(); i++) {
        if (i != 0) {
          sb.append(" ");
        } 
        sb.append(line.get(i));
      }
      
      out.format("Case #%d: %s%n", t, sb.toString());
    }
  }