#include <bits/stdc++.h>
using namespace std;
using vi = vector<int>;
using vii = vector<vector<int>>;
using pii = pair<int, int>;
template <class T>
void print(vector<T> v) {
  bool first = true;
  for (T x : v) {
    if (!first) cout << " ";
    first = false;
    cout << x;
  }
  cout << endl;
}
void pp(pii a) { cout << a.first << " " << a.second; }
int main() {
  int n, m, k;
  scanf("%d%d%d", &n, &m, &k);
  vector<pair<int, int>> ans(n * m);
  for (int i = 0; i < ((int)((ans).size())); ++i) {
    int r = i / m, c = i % m;
    if (r % 2 == 1) c = m - 1 - c;
    ans[i] = {r + 1, c + 1};
  }
  for (int i = 0; i < (k - 1); ++i) {
    cout << 2 << " ";
    pp(ans[2 * i]);
    cout << " ";
    pp(ans[2 * i + 1]);
    cout << endl;
  }
  cout << (int)((ans).size()) - 2 * k + 2 << " ";
  for (int i = (2 * k - 2); i < ((int)((ans).size())); ++i) {
    pp(ans[i]);
    cout << " ";
  }
  cout << endl;
  return 0;
}
