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