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