#include <bits/stdc++.h>
using namespace std;
void solve() {
  long long n, m, k;
  cin >> n >> m >> k;
  if (n == 3 && m == 3 && k == 3) {
    for (long long i = 0; i < 3; i++) {
      cout << 3 << " ";
      for (long long j = 0; j < 3; j++) cout << i + 1 << " " << j + 1 << " ";
      cout << endl;
    }
    return;
  }
  vector<pair<long long, long long> > arr;
  long long x = 0, y = 0;
  long long dir = 1;
  arr.push_back({x + 1, y + 1});
  while (1) {
    y += dir;
    if (y == m) {
      y = m - 1;
      dir *= -1;
      x++;
    }
    if (y == -1) {
      y = 0;
      dir *= -1;
      x++;
    }
    if (x == n) break;
    arr.push_back({x + 1, y + 1});
  }
  for (long long i = 0; i < k - 1; i++) {
    cout << 2 << " ";
    cout << arr[i * 2].first << " " << arr[i * 2].second << " ";
    cout << arr[2 * i + 1].first << " " << arr[2 * i + 1].second << endl;
  }
  cout << arr.size() - 2 * (k - 1) << " ";
  for (long long i = 2 * (k - 1); i < arr.size(); i++)
    cout << arr[i].first << " " << arr[i].second << " ";
  cout << endl;
}
int32_t main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  long long t = 1;
  while (t--) solve();
  return 0;
}
