#include <bits/stdc++.h>
using namespace std;
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  int n, m, k;
  cin >> n >> m >> k;
  vector<pair<int, int> > inds;
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < m; j++) {
      inds.push_back({i + 1, j + 1});
    }
    i++;
    if (i == n) break;
    for (int j = m - 1; j >= 0; j--) {
      inds.push_back({i + 1, j + 1});
    }
  }
  for (int i = 0; i < k - 1; i++) {
    cout << "2 " << inds[2 * i].first << " " << inds[2 * i].second << " ";
    cout << inds[2 * i + 1].first << " " << inds[2 * i + 1].second;
    cout << endl;
  }
  cout << n * m - 2 * (k - 1) << " ";
  for (int i = 2 * (k - 1); i < inds.size(); i++) {
    cout << inds[i].first << " " << inds[i].second << " ";
  }
  cout << endl;
  return 0;
}
