#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using vi = vector<int>;
using pi = pair<int, int>;
int n, m, k;
void solve() {
  cin >> n >> m >> k;
  pi p = {1, 1};
  int d = 1;
  for (int i = 1; i <= k - 1; ++i) {
    cout << 2;
    if (d == 1 && p.second == m) {
      cout << ' ' << p.first << ' ' << p.second << ' ' << p.first + 1 << ' '
           << p.second << '\n';
      ++p.first;
      --p.second;
      d = -1;
    } else {
      cout << ' ' << p.first << ' ' << p.second << ' ' << p.first << ' '
           << p.second + d << '\n';
      p.second += 2 * d;
      if (p.second == 0 || p.second == m + 1) {
        ++p.first;
        p.second = 1;
        d = 1;
      }
    }
  }
  int need = n * m - 2 * (k - 1);
  cout << need;
  while (need) {
    cout << ' ' << p.first << ' ' << p.second;
    --need;
    p.second += d;
    if (p.second == m + 1) {
      ++p.first;
      p.second = m;
      d = -1;
    } else if (p.second == 0) {
      ++p.first;
      p.second = 1;
      d = 1;
    }
  }
  cout << '\n';
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  int t;
  t = 1;
  while (t--) solve();
}
