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