#include <bits/stdc++.h>
using namespace std;
inline long long get_num(char ch) {
  if (ch == '-')
    return 0;
  else if (ch >= 'a' && ch <= 'z') {
    return 1 + (ch - 'a');
  } else if (ch >= 'A' && ch <= 'Z') {
    return 27 + (ch - 'A');
  } else if (ch >= '0' && ch <= '9') {
    return 53 + (ch - '0');
  }
}
int dx[] = {1, 0, -1, 0}, dy[] = {0, 1, 0, -1};
inline int GA(long long n, vector<long long>& vec) {
  for (int i = 0; i < n; ++i) {
    long long x;
    cin >> x;
    vec.push_back(x);
  }
  return 0;
}
inline int GAEG(long long m, vector<long long> vec[]) {
  for (int i = 0; i < m; ++i) {
    long long x, y;
    cin >> x >> y;
    x--, y--;
    vec[x].push_back(y);
    vec[y].push_back(x);
  }
  return 0;
}
const long long MD = 1000000007;
bool isvalid(long long xx, long long yy, long long n, long long m) {
  return (xx >= 0 && xx < n && yy >= 0 && yy < m);
}
long long pw(long long x, long long y, long long dr) {
  if (y == 0) return 1;
  long long o = y / 2;
  long long f = pw(x, o, dr) % dr;
  if (y % 2) {
    return (((f * f) % dr) * x) % dr;
  } else
    return (f * f) % dr;
}
struct st {
  long long x, y, z;
  long long ind;
};
vector<st> v;
int main() {
  long long n;
  cin >> n;
  for (int i = 0; i < n; ++i) {
    long long x, y, z;
    cin >> x >> y >> z;
    st q;
    q.ind = i + 1;
    q.x = x;
    q.y = y;
    q.z = z;
    v.push_back(q);
  }
  while (v.size()) {
    long long x = v[0].x;
    long long y = v[0].y;
    long long z = v[0].z;
    long long ind = v[0].ind;
    v.erase(v.begin());
    st q = v[0];
    long long ss = 0;
    for (int i = 1; i < v.size(); ++i) {
      long long mnx = min(x, q.x);
      long long mxx = max(x, q.x);
      long long mny = min(y, q.y);
      long long mxy = max(y, q.y);
      long long mnz = min(z, q.z);
      long long mxz = max(z, q.z);
      st p = v[i];
      if (p.x >= mnx && p.x <= mxx && p.y >= mny && p.y <= mxy && p.z >= mnz &&
          p.z <= mxz) {
        ss = i;
        q = p;
      }
    }
    cout << ind << " " << q.ind << endl;
    v.erase(v.begin() + ss);
  }
  return 0;
}
