#include <bits/stdc++.h>
using namespace std;
const long long mod = 1000000007;
const long long INF = 1e18;
const long long MAX = 100001;
void solve() {
  long long n, m, k;
  cin >> n >> m >> k;
  vector<pair<long long, long long> > paths;
  long long x = 0, y = 0, dif = 1;
  while (x != n && y != m) {
    paths.push_back({x + 1, y + 1});
    y += dif;
    if (y == m) dif = -1, x++, y = m - 1;
    if (y == -1) dif = 1, x++, y = 0;
    if (x == n) break;
  }
  for (int i = 0; i < (k - 1); i++) {
    cout << "2 " << paths[2 * i].first << " " << paths[2 * i].second << " "
         << paths[2 * i + 1].first << " " << paths[2 * i + 1].second << '\n';
  }
  cout << n * m - 2 * (k - 1) << " ";
  int i = 2 * (k - 1);
  while (i != n * m) {
    cout << paths[i].first << " " << paths[i].second << " ";
    ++i;
  }
}
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  ;
  long long t;
  t = 1;
  for (int i = 1; i <= t; i++) {
    solve();
  }
  return 0;
}
