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